The number of complaints made by consumers against energy firms has leapt by 224% over a single year to reach a record high.
Britain's Energy Ombudsman, an industry watchdog, said it received 10,638 complaints about the sector during the first three months of 2014, up from 3,277 in the same period a year before.
A number of concerns about the energy sector, from spiralling bills to blackouts over the Christmas period, have led to the regulator Ofgem referring the market to the Competition and Markets Authority for a full market investigation. The market is dominated by six large firms.
"Consumer frustration and dissatisfaction is something that we hear about every day and we welcome any attempts by Ofgem to make the energy market fairer," said Lewis Shand Smith, chief energy ombudsman.
"With energy complaints trebling in the first quarter of this year and problems relating to billing the greatest concern, increased transparency is something that should be addressed."
Richard Lloyd, executive director of consumer campaign Which?, said that the "fact that consumer complaints continue to rise is further proof that the energy market is broken and it is right that it has been referred for a full-scale investigation".
There has been a political row over the energy sector in the UK focused on consumers' gas and electricity bills because of the squeeze on household finances.
Ed Miliband, leader of the opposition Labour party, said he would force energy firms to freeze their bills for nearly two years if he is elected at the 2015 general election.
But the governing Conservatives – to the dismay of their Liberal Democrat coalition partners – are removing green levies from energy firms to encourage them to bring down bills.
Green levies are taxes on the energy sector that are used to pay for things such as home insulation. These taxes are passed on by businesses to consumers on their bills.
The government's pledge to remove green levies led to several firms cutting or freezing their energy prices for the coming year.