Energy firm Npower has apologised again for customer service problems that have taken "longer than planned" to be resolved.
In a statement the company said its CEO Paul Massara had written to customers last year to apologise for the issues, which were "caused by the implementation of a new computer system".
The company says a number of measures have been introduced to tackle the problems:
- An extra 650 have been assigned since December to help resolve problems
- Late invoice and complaints data will be published monthly
- An additional £20 million will be invested this year to deal with customer service issues
- A ban on outbound telesales calls if late billing targets are missed