Energy giant E.On is to pay a record £12m penalty, following an investigation into mis-selling by the industry regulator.
Ofgem said it was the largest penalty paid to date by a UK energy supplier.
Its investigation found "extensive poor sales practices" amongst staff selling on the doorstep and by phone.
E.On has apologised to its customers, and has promised to pay compensation to anyone who was mis-sold an energy package.
The company has estimated that the bill for compensation payments is likely to be between £3m and £8m, on top of the £