"Deliberately confusing" energy bills are stopping British consumers switching suppliers, despite an industry shake up which encouraged the public to look around for the best deal.
A report from think tank Centre Forum warns that the amount of people switching their supplier has been in decline since 2012.
The report highlighted a "substantial" decline in switching activity since 2008 where it fell by 5% up to 2012.
That said, the UK is well ahead of EU countries when it comes to switching; the report found 13% of people switched in 2014, well above the EU average of 6%.
"While overall levels of customer engagement are still good by European standards, there are clear barriers to greater consumer activity. There is also concern that the situation has been getting worse in recent years," said the report.
"The biggest barrier is the confusing plethora of tariffs and the obfuscatory way in which information is presented. Customers more frequently complain about receiving too much information, and having too much choice, rather than too little. Bills are complex and like for like comparisons difficult."
Comparethemarket.com, head of energy, James Padmore said: "The report underlines the fact that the energy market is broken. Consumers struggle to make sense of energy bills and too many remain on uncompetitive tariffs because they are unsure of how to compare deals based on their current usage and expenditure.
"We estimate that if everyone moved to the best energy tariff for them, the 'energy dividend' back into the pockets of UK consumers would be in the region of £4bn (€5.5bn, $5.8bn) – an indication of the overpayments caused by automatically rolling on to standard tariffs and not reviewing bills.
"Consumers need to be able to compare tariffs like for like and make informed decisions about the best deal for them. The report we have commissioned clearly shows that, at present, the energy industry falls woefully short of this requirement."