Britain's energy regulator Ofgem revealed in a regulatory note this morning that between September 2013 and December 2014 npower issued 500,000 late bills to customers but gave little or no detail on how these bills were calculated. The bills were also inaccurate.
During this time, there were 2 million complaints and a majority of these grievances were related to late or inaccurate bills.
Ofgem said "npower often failed to resolve these issues promptly, pursued debts which were in dispute and failed to keep its own commitments to customers on billing. This caused significant distress and worry for many."
The regulator added that this was mainly due to a failure in npower's IT systems in 2011.
"npower failed its customers. Not only have its billing and complaint handling procedures been chaotic, it treated many of its customers poorly, which is completely unacceptable," said Dermot Nolan, Ofgem chief executive. "npower's management failed to act quickly enough to protect its customers when things went wrong with changes to its IT system."
"It's important that all suppliers ensure they follow the principles of treating customers fairly at all times. The payment of £26m sends a strong message to the industry that we expect them to act quickly and effectively to ensure a good customer experience."
npower will pay back £26 million to customers in a redress package and Ofgem added customers do not need to do anything as npower will contact those who have been worst affected.