ScottishPower has received the highest number of complaints ever recorded for a UK energy supplier.
That’s according to new figures, which revealed there were more than 1,000 complaints per 100,000 customers in the final quarter of last year.
Figures rose 588% throughout 2014, according to consumer advocate Citizens Advice.
The number of complaints about other major suppliers – British Gas, SSE, EDF Energy and npower – however fell in the last quarter of 2014.
npower had been at the bottom of the list for customer service but Citizens Advice said the supplier has made improvements but is still performing poorly compared to most other firms.
Overall, the total number of complaints about the Big Six energy providers increased by nearly 500% in 2014.
Earlier this year, ScottishPower was banned from selling energy for 12 days after failing to meet Ofgem’s targets.
Gillian Guy, Chief Executive of Citizens Advice said: “New billing systems are routinely failing energy customers. In the last few years, four of the largest firms have introduced new billing systems and their implementation has caused chaos for consumers.
“Thousands of customers have been hit by delayed and incorrect bills which have resulted in extreme frustration and significant debts.”
Neil Clitheroe, CEO of ScottishPower Retail and Generation said the company had its “most challenging period” towards the end of last year when they introduced a new £200 million IT system for customers.
He added: “We apologise unreservedly to any customers who have experienced account issues. To make improvements we have added 700 new customer service advisors and we worked closely with Ofgem on call waiting times, outstanding bills and Ombudsman complaints.
“We also agreed with Ofgem to stop outbound sales for a two week period. Recently our call answering times have been amongst the best in the industry and outstanding complaints have been reduced significantly. We remain fully committed to resolving outstanding issues and ensuring that no customers will be left out of pocket.”