Vodafone has been fined £4.6m ($5.6m) by Ofcom, the UK telecom regulator. This is over a series of customer failings in the UK.

This fine follows the conclusion of two probes by Ofcom, both of which are said to have lasted for eighteen months.

The British telecommunications giant was being investigated for two issues, one was the way it handled customer complaints and the other was its delivery of services to pay-as-you-go customers. Ofcom said it found significant failings in both these cases.

Ofcom accused Vodafone of misleading 10,452 pay-as-you-go customers over top-up payments. It said the mobile phone account of these users failed to get credited even after customers had paid for a top-up.

In total, top-ups amounting to £150,000 were lost over a 17-month period, the regulator said. "Vodafone also failed to act quickly enough to identify or address these problems", it added.

According to unnamed sources cited by Sky News, these failures were in line with the initial findings that Ofcom had published earlier this year. With regards to the customer complaints probe, Ofcom had earlier said it will check if Vodafone, which has 20 million mobile customers in the UK, had handled these in a way that complies with procedures that are transparent, accessible and effective.

On Wednesday, Ofcom said Vodafone had failed in this department as well. The telecom firm's customer service agents are said to have not given "sufficiently clear guidance" on what constituted a complaint. Also, some complaints were said to have not been handled "in a fair, timely manner" amid poor processes.

In response, Vodafone has apologised for its failings. The BBC cited it as saying, "It is clear from Ofcom's findings that we did not do that often enough or well enough on a number of occasions. We offer our profound apologies to anyone affected by these errors."