Around 500,000 low energy users, who tend to be on the lowest incomes, could be advised on the wrong tariffs, under new proposals by Ofgem, Which? said.
Rising energy bills remain one of consumers' top financial concerns yet six in 10 of us have never switched supplier as people are left baffled by the vast array of complicated tariffs.
These current proposals are far too complicated and will fail to achieve their aim of making it easier for people to find the best deal, with three-quarters of people being asked to compare prices that are not based on their energy usage.
More top news
After seven days of spectacular chaos, the fog is now starting to lift. Tom Bradby takes a look at what could lie ahead for the UK.
Bank of England governor signals possible interest rate cut saying "monetary policy easing will likely be required".
A look at how Mouquet Farm, north of Pozières in France, became a pivotal battleground during the Battle of the Somme.