The internet service providers Talktalk have between them been fined £3 million by telecoms regulator Ofcom.

The fine was levied after the ISPs incorrectly issued bills to 65,000 customers for services they didn't receive, in particular to customers who had closed their accounts. Tiscali UK was bought by Talktalk in 2009.

The independent regulator opened an investigation into the two companies in July 2010 after receiving more than 1,000 complaints from customers. It found that bills were wrongly issued to over 62,000 customers between 1 January and 1 November 2010. Following the investigation, Ofcom gave the companies a deadline of 2 December 2010 to "take steps to sort out their billing problems".

However, as Computeractive reported in February this year, complaints continued to come in, despite changes to Talktalk and Tiscali UK's customer management systems. Ofcom found that a further 3,000 customers were incorrectly billed between December 2, 2010 and March 4, 2011.

Talktalk said it was "disappointed" at receiving what amounts to the largest fine Ofcom has given to a telecoms firm, though Ofcom said the amount reflected the seriousness of the breach of its rules.

It warned that the fine could have been much larger had Talktalk and Tiscali UK not already made goodwill payments and refunds totalling £2.5m to over 65,000 affected customers.