The 'Big Six' energy firms received an average of more than 15,000 complaints a day according to new data.
Information from the gas and electricity firms showed the high number of complaints over the last quarter of last year, but also highlighted the vast majority of them were resolved by the next working day.
EDF was the worst firm in terms of customer complaints with 8,072 complaining per 100,000 customers or 440, 317 complaints in total - double the figure of the next firm on the list, Npower, which had 4,001 complaints per 100,000 customers.
E.On and British Gas were next in the complaints table with 3,023 and 1,435 complaints per 100,000 customers respectively, whilst Scottish Power had the least number of complaints out of the 'Big Six' with 1,359 per 100,000 customers.
Despite ranking lowest in number of complaints however, Scottish Power had the lowest proportion of complaints resolved at the end of the next working day at 68%.
Many of the complaints to the energy firms were over billing or accounts, but other issues such as boilers not working and even customer service also factored in.
Energy regulator Ofgem has encouraged energy firms to publicise these complaints in an easily accessible manner to customers - demanding that the figures be accessible within two clicks of landing on the company's home page.
Ofgem consumer partner, Philip Cullum, said: "Ofgem is now shining a spotlight on individual supplier performance, by getting suppliers to publish better data more often and more prominently.
"This should mean that suppliers improve the way they handle complaints and that the things they learn from complainants lead to better services."
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