Energy companies and Ofgem should further simplify bills following a new survey showing 60% of consumers are still confused by them, according to the Energy Advice Line.
Julian Morgan, managing director of the price comparison, switching and advice service for energy users said the information provided to consumers about gas and electricity supplies needed to be clearer.
"This survey simply confirms what we already knew - consumers still find their energy bills baffling and this stands in their way of switching suppliers, because they can't compare tariffs like for life," Mr Morgan said.
"It's in the interest of energy companies to have complicated bills, which is why the energy regulator needs to step in and impose new rules so suppliers make the information they send out clear and simple.
"Previous measures put in place by Ofgem clearly haven't worked, and they need to go back to the drawing board."
Ofgem's previous reforms included a requirement for suppliers to provide details of the cheapest available tariff on customers' bills, yet almost half of those surveyed said they have seen no difference. More than half are unable to recall information about cheaper deals.
However, more than a quarter of those surveyed admitted they don't bother to check any details on their energy bills beyond the amount they have to pay. Younger consumers are the most ignorant; almost seven in ten of those aged between 18 - 35 admit they don't fully understand their bills.
Energy suppliers were voted the worst offenders for sending confusing bills, worse than water companies, mortgage lenders, councils, phone companies and credit card lenders.
"The complicated nature of energy bills is obviously a problem that has to be tackled," Mr Morgan said.
"It is unacceptable that consumers are still baffled by these bills, when energy now forms a significant proportion of household expenditure. How can energy users take control of their energy supplies and make informed choices about which supplier and tariff to go for, when they are bewildered by the information on their bills?"
But Mr Morgan said there was also a role for consumers to play.
"Energy users need to do themselves - and their bank balances - a big favour and actually read their bills carefully. We understand that this won't be the highlight of their day, but it needs to be done to avoid paying over the odds for gas and electricity.
"This is where the Energy Advice Line can help. Consumers who don't understand their bills, and would like to switch suppliers, can call us free of charge for help.
"We can explain the bill, search the market for the cheapest deal and arrange the switch accordingly, and it will cost nothing. It makes much more sense than remaining baffled, or worse, not opening your bill at all."
The Energy Advice Line is one of the UK's leading price comparison and switching services for business and domestic energy customers. It is also an advocate for energy market reform and has campaigned for a better deal for energy users, including calling for a ban on cold calling and changes to regulations to make it easier for all consumers to switch suppliers.
The service is completely independent and free. Consumers can quickly and simply search the market for the best available energy deals from an extensive panel of small and large energy suppliers. The service also offers a free advice line for business energy customers.
For further information visit energyadviceline.org.uk