Energy firm npower has blamed the installation of its new billing system for its failure to send out a number of bills and statements and for direct debit payments not being properly set up.
The firm has written to its 5.4 million customer account holders to apologise, with npower CEO Paul Massara explaining that the firm has been in discussions with energy regulator Ofgem to resolve the issue.
"In recent months, we've let many of our domestic customers down and I wanted to write to each of them personally to say sorry," he said.
The problems arose after npower installed a new system to manage its customer accounts data. Computing is awaiting confirmation from npower of the name of the system in question.
"Unfortunately, despite our best efforts, the installation didn't go as smoothly as planned," npower said on its website.
"The transfer to our new system caused problems we weren't expecting with some of the letters and bills we send out," it added.
The firm explained that it needed to put a new system in place so it could get a "much better picture of our customers' needs" so that it could "deliver a much better service".
"We're using software that can manage a vast database, processing information about many different parts of the business at the same time. This includes things like finances, customer account details and customer relationship information. But we want that software to be as up to date as possible," the company said.
CEO Massara promised customers that they would not lose out financially as a result of the ongoing issues.
Neil Kinson, vice president for EMEA at IT process automation firm Redwood Software, said a backend failure can have a knock-on effect on frontline services.
"It's like a domino effect; a persisting failure in the billing department can lead to greater pressure on the provider's website and call centres, as customers look to question the mistake," he said.
Npower claims that it has an additional 800 staff working to address its billing issues.
Just last week, the energy giant confirmed plans to cut 1,460 jobs in the UK. It is, however, on the lookout for people with big data skills, having attended the SAS Careers Fair at Brunel University last week.
By eliminating high entry costs for big data analysis, you can convert more raw data into valuable business insight.
A discussion of the "risk perception gap", its implications and how it can be closed