Scottish Power, EDF, and British Gas have been named the worst performers in a new annual survey conducted by consumer group Which?. The three major energy firms each received overall scores under 60%, reflecting significant dissatisfaction among customers.
Scottish Power received the lowest rating, with an overall score of just 56%. Customers particularly criticized the company’s handling of complaints, earning it the worst marks in that category. Meanwhile, EDF followed closely behind with a score of 58%. The company’s customer service was flagged for inadequate monitoring of phone lines and email support, which fell short compared to other providers. British Gas came in third with a score of 59%. Despite offering decent support for those in need, the company struggled with resolving complaints and switching customers, according to the survey findings.
Top-Rated Suppliers Shine Amid Customer Discontent
In contrast, E (Gas and Electricity) topped the rankings with an impressive score of 79%. The company earned high marks for its customer service, ease of contact, and the clarity of its statements. A staggering 86% of E customers reported that they would recommend the provider to others. Octopus Energy placed second with a score of 74%, while 100Green and Sainsbury’s Energy followed with ratings of 72% and 71%, respectively.
The survey, which surveyed almost 12,000 energy customers during September and October 2025, also included an in-depth assessment of the internal operations of 17 major energy firms. While the top companies continue to excel, Which? Energy editor Emily Seymour warned that larger suppliers like Scottish Power, EDF, and British Gas must make significant improvements to avoid losing customers. “With fixed tariffs now reliably cheaper than the energy price cap, there is no need for customers to tolerate poor service or poor value for money,” Seymour noted.
Both British Gas and EDF have responded to the findings, citing ongoing investments to improve customer service. British Gas, owned by Centrica, highlighted a 20% annual decrease in complaints over the past two years and improvements in its call center and support services for vulnerable customers. EDF emphasized its efforts to help customers with additional needs, pointing to a Trustpilot rating of 4.8 from over 154,000 reviews.
Scottish Power, for its part, argued that its performance is better reflected in the Citizens Advice scorecard, which it believes offers a more transparent methodology for evaluating customer service. However, the company acknowledged the areas it still needs to improve, especially following the critical feedback from the Which? survey.
