SSE, the energy supplier fined £10.5m for mis-selling earlier this month, expects to pay out around £1.5m in compensation.
The firm told MPs it made around £45 a year from each of the estimated 23,000 customers affected by mis-selling, and expected to pay them compensation of between £65 and £70.
SSE – one of eight suppliers questioned today by the Energy and Climate Change Committee – promised to compensate any customer who had lost money.
After the hearing an SSE spokeswoman said the £60 to £75 figures were "typical" at the moment but affected customers were being treated on a case-by-case basis, adding: "We will make right any financial loss."
SSE's deputy chief executive, Alistair Phillips-Davies, said the company had changed its training and audit procedures to correct the problem and admitted that the company's actions had affected trust among consumers.
"I would have thought for some customers, it would have decreased the level of trust, although for others it would not," he said. "As soon as we knew there was mis-selling, we took action."
He said some feedback from customers suggested they were pleased with how the company had handled the issue and he said SSE had agreed to accept the £10.5m fine from regulator Ofgem, who found that the company had been guilty of "prolonged and extensive" mis-selling.
MPs also repeatedly pressed suppliers EDF and E.On to "come clean" about their own practices.
Jim Poole, director of residential customers at EDF, said he was confident that the company's controls were robust enough to ensure there was no widespread mis-selling.
Labour MP John Robertson asked E.On chief executive Tony Cocker: "Are you squeaky clean?" to be answered: "It's too early to say."
Robertson replied: "I would expect a company like yours to know. You do know. Come clean now."
Cocker said: "We're working hard to ensure that we're clean."
Robertson said: "Not good enough."
Juliet Davenport, the CEO and founder of renewable energy supplier Good Energy, told MPs that the market needed further competition.
She said: "Making sure there are more players in this market, that is the key to rebuilding trust."