Energy firms came under fresh fire last night after evidence came to light of them using dubious sales tactics to sell expensive tariffs.
Undercover researchers discovered that anyone who switched tariff based on the sales patter of in-store representatives of the big energy companies could be worse off by hundreds of pounds.
Energy companies' salespeople in supermarkets and shopping centres told researchers they would make annual savings of between £20 and £142. But the customers would actually have been between £39 and £311 worse off if they had taken up the deals, according to Which?.
In a separate investigation of energy companies' call centres, people who called up and asked for the cheapest deal did not always get accurate information and quotes. British Gas and Eon got it wrong, Which? said.
Meanwhile, when researchers asked salespeople in supermarkets and shopping centres about better deals, only two out of 13 admitted there might be better deals available. The news comes as pressure mounted on the Big Six energy firms to offer fairer prices and help vulnerable people in fuel poverty.
By last night, more than 86,000 people had signed up to the Big Switch prices campaign being run by Which? with online campaigners 38 Degrees. Meanwhile the "End the Big Six Energy Fix" fuel-poverty campaign launched in The Independent last week has attracted 7,000 supporters.
Discussing the sales tactics used by energy companies, Richard Lloyd, executive director at Which?, said: "It's simply not good enough for energy salespeople to be quoting misleading individual savings to people who sign up to switch in supermarkets."
Which? researchers spoke to reps from SSE (selling M&S Energy tariffs), British Gas (selling Sainsbury's Energy deals), EDF Energy and Eon. They posed as customers who did not have the name of their tariff or their consumption figures with them. They said they only knew the name of their energy supplier and how much they were paying a month.
They were told by salespeople that by switching to Sainsbury's Energy Standard tariff they would be better off by up to £68. But they would actually have been worse off by up to £311, said Which?.
Over at M&S, salespeople told researchers they would be up to £46 better off with the the M&S Energy Standard rate, but Which? calculated that switching would leave people up to £95 worse off.
The energy firms hit back at Which?'s figures saying their researchers were given estimates and therefore it didn't make for a fair comparison. But Richard Lloyd said: "It's little wonder that trust in the energy sector is so low."
Case study: 'It's like a cartel'
Rita Young, 76, a widow from Peterborough, lives on pension and pension credit
"I'm a widow. I live on £161 per week, £63 of that goes on fuel. It's not pleasant. I make sure I don't get up until late so I don't have to put the heating on. I stay in bed and watch television in the morning rather than get up. That saves another couple of hours of fuel. I turn it off an hour before I go to bed at 9 o'clock, that way you save a bit.
"I wear lots of cardigans and use lots of blankets. It's annoying, I've got things I want to do but you've got to spend your day thinking about fuel.
"I get my state pension and, at present, pension credit, but even that they're cutting out from April so I'm going to be losing £3 a week on my pension credit. When the state pension goes up £5 a week, I'll only get a £2 increase. I'm with E.ON but all the suppliers are the same – one puts it up then all the others put it up. It's like a cartel. They're not doing anything to help us."