EDF Energy has acknowledged that its customers were caused significant disruption when the firm introduced a new IT system in 2011 and has publicly apologised for this.
Ofgem said that the firm's payment of £3 million to vulnerable customers was a "step in the right direction".
EDF Energy failed to have sufficiently robust processes in place when they introduced a new IT system and this led to the unacceptable handling of complaints.
Their commitment to putting things right and paying £3 million to the Citizens Advice Energy Best Deal Extra scheme and the Plymouth Citizen Advice Bureau's Debt Helpline to benefit vulnerable customers is a step in the right direction to rebuilding consumer trust.
More top news
Animal loving American Chuck Blazer became football's 'Mr 10 per cent' at the corrupt centre of Fifa.
More than 80% of samples from Asda tested positive for campylobacter, while Tesco was the best performing supermarket.
The boy was reportedly only discovered missing when the bus returned to the school and the boy's mum was waiting for him.