If you search "which energy supplier is best," you'll find a neat answer: Octopus Energy. Scroll a bit further and you'll see Ecotricity at the top of the official Citizens Advice table. Look at the Which? 2025 satisfaction survey and Octopus tops that too - at 74%.
So which energy companies actually have bad customer service? The answer depends on where you look. Different data sources measure fundamentally different things, and most comparison articles collapse them into a single "best" that hides the real story.
So we pulled four independent datasets - Citizens Advice (the statutory quarterly star rating), Which? (the annual customer satisfaction survey), DataEQ's social sentiment index tracking half a million posts, and Ofgem's own enforcement record - and put them side by side. The picture that emerges is more useful, and more damning in places, than any single ranking.
What you'll learn in this article:
- The full Citizens Advice complaints league table - all 16 energy firms ranked
- Which? customer satisfaction results - who scores worst
- Why we don't use Trustpilot - the self-selection problem
- Social media sentiment - the unfiltered public verdict
- Octopus Energy profile - who owns it, tariffs, Saving Sessions and more
- OVO Energy evaluated - what went wrong
- Ofgem enforcement actions - which suppliers have been fined
The Four Data Sources - and What They Actually Measure
Before getting to the rankings, it's worth being precise about methodology. How SwitchInsights tracks supplier complaints: we pull from four independent sources - Citizens Advice (the statutory star rating), Which? (annual customer survey), DataEQ's social sentiment index, and Ofgem's own enforcement record. No single dataset captures the full picture, which is why the rankings sometimes disagree with each other. We refresh when Citizens Advice publishes a new quarterly scorecard or when Which? or DataEQ updates their data. Public review platforms like Trustpilot are discussed separately below - we don't use them for scoring because of a well-documented self-selection bias.
Citizens Advice Star Rating
Statutory quarterly rating. Covers complaints volume (weighted by severity), call wait times, billing accuracy, and customer commitment scheme membership. Updated Q4 2025. Only includes suppliers with 25,000+ customer accounts.
What it captures: The structural behaviour of a supplier's complaints handling - not customer perception.
Which? Customer Survey
Annual survey of ~12,000 energy customers (Sep–Oct 2025). Scores include satisfaction, likelihood to recommend, and a behind-the-scenes assessment of supplier practices including complaints performance, smart meter targets, and switching processes.
What it captures: Lived customer experience, blended with process auditing.
DataEQ Social Sentiment
Analysis of 500,000+ social media posts (verified by human annotators) across energy brands, with a net sentiment score. Also measured response rates and response times to critical posts.
What it captures: Unsolicited public sentiment - the closest thing to unfiltered customer opinion.
Ofgem enforcement record
Formal Ofgem enforcement decisions, redress orders and Market Compliance Review findings for each licensed supplier. Public record on ofgem.gov.uk.
What it captures: The regulator's judgement on supplier behaviour, especially towards vulnerable customers.
The Full League Table: Citizens Advice Q4 2025
This is the authoritative statutory benchmark. Citizens Advice has a legal remit to publish this data quarterly. The complaints component is weighted by severity - a complaint that reaches the Energy Ombudsman carries more weight than a single call to the Citizens Advice consumer service. The model specifically penalises suppliers where consumers had to contact multiple organisations because their problem wasn't resolved.
Citizens Advice Domestic Supplier Star Rating - Q4 2025 (Oct–Dec 2025)
Scores out of 5. Suppliers with fewer than 25,000 customer accounts are excluded from the main table. Source: Citizens Advice, published March 2026.
| Rank | Supplier | Overall | Fewer Complaints | Wait Times | Billing & Metering | Commitments |
|---|---|---|---|---|---|---|
| 1 | Ecotricity | 4.0 | 4.0 | 3.3 | 5/5 | |
| 2 | Outfox Energy | 3.0 | 4.4 | 4.1 | 5/5 | |
| 3 | Octopus Energy | 3.5 | 4.0 | 3.4 | 5/5 | |
| 4 | Co-Op Energy | 3.5 | 4.0 | 3.3 | 5/5 | |
| 5 | E.ON Next | 3.0 | 3.6 | 4.3 | 5/5 | |
| 6 | 100Green | 3.5 | 4.8 | 3.8 | 0/5 | |
| 7 | Good Energy | 4.0 | 3.0 | 3.4 | 3/5 | |
| 8 | E (Gas & Electricity) | 1.0 | 4.4 | 5.0 | 3/5 | |
| 9 | ScottishPower Ofgem action | 2.0 | 4.0 | 2.8 | 5/5 | |
| 10 | OVO Energy | 2.0 | 2.0 | 3.8 | 5/5 | |
| 11 | So Energy | 1.5 | 3.4 | 2.6 | 5/5 | |
| 12 | Utility Warehouse | 2.5 | 3.0 | 2.3 | 3/5 | |
| 13 | EDF Energy | 2.0 | 2.2 | 3.0 | 5/5 | |
| 14 | British Gas Ofgem action | 1.0 | 3.6 | 1.4 | 5/5 | |
| 15 | Utilita Ofgem action | 0.5 | 3.6 | 2.7 | 3/5 | |
| 16 | TruEnergy Ofgem action | 2.0 | 2.4 | 1.9 | 0/5 |
A few things stand out. Ecotricity and Outfox Energy top the table despite being small suppliers with limited brand recognition - a reminder that scale and service quality are not correlated. 100Green scores 4.8/5 for contact wait times but gets zero for customer commitments (it has not signed up to the Energy Switch Guarantee or Vulnerability Commitment), which costs it dearly in the overall ranking. And E (Gas & Electricity) earns a perfect 5/5 for billing and metering - the highest score in the table - while sitting eighth overall because its complaints volume score pulls it down.
Note on Utilita's position: Utilita finished 15th out of 16. A company spokesperson disputed this, saying Citizens Advice methodology "penalises us unfairly due to its interpretation of complaints, significantly impacting our overall ranking" and that Ofgem and Energy Ombudsman data shows them as consistent top performers. This isn't a trivial objection - the Citizens Advice model weights escalation heavily, and prepayment meter suppliers like Utilita tend to deal with more complex, multi-agency cases by the nature of their customer base. It's a legitimate methodological tension, not a PR deflection.
Which? 2025 Survey: When Customers Vote with Their Words
The Which? annual survey is the largest representative customer satisfaction study in the sector. ~12,000 energy customers were polled in September–October 2025 and asked to rate their supplier on satisfaction and likelihood to recommend. Which? then overlaid its own behind-the-scenes assessment of each supplier's practices.
Top performers: Octopus Energy led at 74%, with nearly 90% of customers expressing satisfaction. Utility Warehouse ranked second at 73%, followed by 100Green at 70%.
Bottom performers: British Gas, Scottish Power, and OVO Energy all scored below 60%. British Gas ranked among the worst for complaint volume, complaint resolution efficiency, smart meter target performance, and switching processes. OVO received the lowest customer satisfaction score in the survey at 56%.
Octopus's trajectory is notable. It has risen from 11th place in Citizens Advice rankings two years ago to 3rd now, while simultaneously becoming the UK's largest energy supplier. Achieving that combination - rapid growth while improving service - is genuinely unusual in the sector. The two more commonly go in opposite directions.
Why We Don't Use Trustpilot
Trustpilot scores in the energy sector are almost uniformly high - and that should make you suspicious. It's why the SwitchPilot Score and this article's rankings don't use Trustpilot at all.
Several of the largest UK suppliers hold Trustpilot ratings well above 4 stars from very large review bases. And yet three of them sit in the bottom half of the Citizens Advice statutory table: EDF is 13th, OVO is 10th, British Gas is 14th. Those two pictures cannot both be true; one of them is measuring the wrong thing.
The explanation is structural. Trustpilot reviews are predominantly left by customers at two moments: immediately after switching (when the experience is fresh, the journey was smooth, and a review request landed in their inbox) and after a severe negative experience (when they're angry enough to seek out a platform). The millions of customers who've been on a default SVT for five years and have never interacted meaningfully with their supplier don't leave Trustpilot reviews. They are, in effect, invisible to that dataset.
Citizens Advice, by contrast, captures the complaints those silent customers eventually raise - and weights them by severity. The two datasets aren't measuring the same population. That is why we anchor on Citizens Advice, cross-reference against Which? and DataEQ, and treat public review platforms as directional context only.
| Supplier | Trustpilot signal | Citizens Advice rank | Divergence |
|---|---|---|---|
| EDF Energy | High rating | 13th / 16 | ↓ Looks better than it is |
| OVO Energy | High rating | 10th / 16 | ↓ Looks better than it is |
| British Gas | High rating | 14th / 16 | ↓ Looks better than it is |
| E.ON Next | Aligned with CA | 5th / 16 | ≈ Consistent |
| Octopus Energy | Aligned with CA | 3rd / 16 | ↑ Consistent across sources |
| Ecotricity | Small review base | 1st / 16 | ↑ Tops Citizens Advice |
The divergence is starkest for EDF. Its spokesperson attributed its rising Citizens Advice score to staff training and ongoing investment - which is plausible - but also pointed to its large Trustpilot review base as evidence of strong service. Those two statements aren't incompatible, but they're measuring different things, and conflating them misleads customers.
Social Media: The Unfiltered Verdict
The most compelling data point in this piece is one that rarely gets cited. Social analytics firm DataEQ, working with Unstructured, analysed over half a million social media posts about UK energy suppliers across a three-month window. Each post was sentiment-rated by human annotators and used to produce a Net Sentiment score for each supplier.
The industry average Net Sentiment was −53.6%. That means even in a normal period, more than half of all public energy-related social conversation is negative. This isn't a crisis reading - it's the sector's baseline.
Octopus Energy achieved the best score in the industry by a significant margin. British Gas ranked last. Scottish Power and OVO were also at the bottom. But the most striking finding was operational: 51.7% of consumers' most critical posts - those explicitly requiring a supplier response - went completely unanswered. Of those that did receive a response, the average wait time was over seven hours.
This matters beyond reputation management. Social media is increasingly where customers in distress turn first - and the sector is systematically ignoring more than half of them.
What the DataEQ data reveals about British Gas specifically: British Gas and ScottishPower drew particular criticism for missed engineer appointments and the handling of vulnerable customers. OVO drew sustained negative sentiment around direct debit increases and billing disputes. Octopus attracted negative posts too - primarily around unmasked door-to-door sales representatives - but at significantly lower volume and intensity than the legacy suppliers.
Ofgem's Enforcement Record: The Regulatory View
Regulators provide a fifth data point. Ofgem's Market Compliance Review assessed how suppliers were treating customers experiencing payment difficulties and identified three tiers of failure.
Severe weaknesses: TruEnergy, Utilita, and ScottishPower. Utilita and ScottishPower were issued with formal enforcement notices. British Gas was subject to a separate urgent investigation by Ofgem following a Times investigation into forcible prepayment meter installations against vulnerable customers.
Moderate weaknesses: A further 11 suppliers, including British Gas, EDF, OVO, Good Energy, So Energy, and Utility Warehouse, were found to have identifiable issues in their treatment of customers facing financial difficulty.
Minor issues only: Ecotricity, Octopus, and a small number of others.
The enforcement notices against ScottishPower are particularly notable given that the same supplier holds a high Trustpilot rating. There is no universe in which those two facts reflect the same underlying customer experience.
Octopus Energy: Inside the UK's Largest Energy Firm
So who owns Octopus Energy? The company was founded in 2015 by Greg Jackson, who remains CEO of Octopus Energy Group. The group now operates in 17 countries and has grown into the UK's largest domestic supplier by customer numbers, overtaking British Gas in late 2024 with a 23.7% market share.
Octopus offers a range of tariff types. Its standard import tariff - Flexible Octopus - tracks the Ofgem price cap and charges a flat rate for electricity and gas. For solar panel owners, the Outgoing Octopus tariff pays a fixed export rate for surplus electricity fed back to the grid. This export tariff is one of the more competitive on the market, and it sits alongside the standard import tariff as part of a broader product suite designed for households generating their own power.
For customers on smart meters, Agile Octopus offers time-of-use pricing where rates change every half hour. This means cheaper electricity outside peak times (typically 4pm-7pm) and occasionally negative pricing overnight. The Outgoing Octopus tariff complements this for households that export surplus solar generation.
Demand Flexibility Service and Saving Sessions
Octopus was one of the most active participants in the National Grid's Demand Flexibility Service during winter 2023/24. Through its Saving Sessions programme, Octopus customers were paid to reduce electricity use during periods of high grid demand. Over 1.5 million sessions were completed, making it the largest residential flexibility programme run by any of the energy firms in the UK.
This kind of demand-side participation is becoming central to how the grid manages peak load. Octopus Energy Group has invested heavily in the technology platform (Kraken) that powers this - and has licensed it to other energy firms globally, including Tokyo Gas and EDF in Europe.
How Octopus reviews compare to the regulatory data
Octopus's public review scores broadly align with its Citizens Advice and Which? performance. That consistency across independent sources - regulator, survey, and public sentiment agreeing rather than contradicting each other - is what sets Octopus apart from suppliers like EDF or British Gas, where public review platforms paint a much rosier picture than the regulatory data.
The one recurring complaint in Octopus reviews relates to tariff transfers during home moves. Customers on smart tariffs like Agile or Outgoing Octopus sometimes lose their tariff during a property switch and are defaulted to the standard flat rate import tariff until the new account is fully set up. This is a known friction point, but it affects a small minority of customers.
Evaluating OVO Energy as a Supplier
OVO Energy is the UK's third-largest supplier by customer numbers, largely because of its 2020 acquisition of SSE Energy Services. That merger brought millions of legacy SSE customers onto OVO's systems - and the integration has been bumpy.
In the Citizens Advice Q4 2025 table, OVO sits 10th out of 16 energy firms. Its weakest scores are for complaint volumes (2.0/5) and contact wait times (2.0/5). In the Which? 2025 survey, OVO received the lowest overall customer satisfaction score of any supplier at 56%.
The social media picture is equally poor. OVO drew sustained negative sentiment around direct debit increases, billing disputes, and account migration errors - many of which trace back to the SSE integration. Public review platforms tell a different story, but as we've shown above, those platforms capture the switching experience, not the ongoing service reality for millions of legacy customers who never chose OVO in the first place.
OVO's core problem is structural. Absorbing SSE's customer base tripled OVO's size overnight, but the company's service infrastructure has not scaled to match. The result is a supplier that performs like a mid-table energy firm on every regulatory and survey measure, and only looks better on self-selected public review platforms where recent switchers skew the picture positive.
Where Does This Leave Fuse Energy?
Fuse Energy - the subject of our recent supplier profile - does not yet appear in the Citizens Advice main table. It has fewer than 25,000 customer accounts against the 25,000-account threshold, placing it in the "smaller suppliers" dropdown rather than the ranked table. The absence from the main statutory dataset is not a criticism - it's simply where the company sits in its growth trajectory. As customer numbers scale past 25,000, it will enter the full table.
So Who Is Actually Best?
Honestly, the answer depends on what you're trying to know.
If you want the supplier with the lowest complaint escalation rate and the most accurate billing, Ecotricity tops the statutory data. If you want the supplier most consistently praised by its own customers across multiple independent studies, Octopus Energy leads - and is the only large supplier to perform consistently well across Citizens Advice, Which?, and social sentiment simultaneously. If you want the supplier with the fastest response times, 100Green and Outfox Energy stand out in the Citizens Advice contact wait data. If you want the supplier with the fewest Ofgem enforcement concerns, the answer is broadly any of the smaller independents or Octopus.
What the data firmly and consistently contradicts is any reading that places British Gas, OVO, or ScottishPower in the top half of the market for customer service. Their public-review scores may look reasonable; everything else - Citizens Advice, Which?, social sentiment, Ofgem enforcement - points the other way.
The bigger picture: The sector improved meaningfully in 2025 - average complaints fell to roughly 0.9 per 100 customer accounts by late in the year, down from post-crisis peaks. But household energy debt hit a record £4.4bn, and the customers carrying that debt are disproportionately represented in the parts of the data Trustpilot doesn't capture. The gap between how suppliers look on review platforms and how they're actually performing for the most financially pressured customers is one of the clearest diagnostics of what's still broken in this market.