"Vodafone has been fined a record £4.6 million by the telecoms watchdog for leaving thousands of customers out of pocket in a disastrous IT blunder.

Ofcom found that the operator mishandled complaints and failed to pay into the accounts of more than 10,000 pay-as-you-go customers when they topped up their credit.

The top-up error, which cost customers £150,000 over 17 months in 2014 and 2015, stemmed from the moving of 28.5 million accounts to a new billing system. Errors in billing data and price plans caused so much protest that it made Vodafone the most complained-about mobile network in Britain. The technical issues were resolved by April 2015 and all accounts are now on the new system, Vodafone said.

Lindsey Fussell, Ofcom’s consumer group director, said: “Vodafone’s failings were serious and unacceptable, and these fines send a clear warning to all telecoms companies.”"