Complaints against UK household energy suppliers rose by 26 percent over the months of July to September with EDF Energy scoring worst, Consumer Focus data showed on Friday.
The report from the government funded group said that a major driver of the increase in complaints was rise in prices announced by the 'Big Six' energy suppliers over the summer.
It is disappointing, but perhaps not surprising, that complaints on energy issues have risen at a time when energy bills are increasing, said Adam Scorer at Consumer Focus.
The energy utility which saw the highest increase in complaints was EDF Energy, with complaints up 91 percent on the same quarter last year.
Like in the second quarter, SSE topped the table with the lowest complaints score.
The quarterly data ranks Britain's six largest energy suppliers according to customer complaints received by Consumer Focus, Consumer Direct and the Energy Ombudsman, which handles complaints that are unresolved after eight weeks.
Its current complaints performance is unacceptable and the company must take further steps to tackle this, Scorer said.
E.ON, EDF, SSE, British Gas, npower, and Scottish Power all announced price rises taking effect this year.
(Reporting By Ethan Kent Bilby; Editing by Henning Gloystein)