BT billed me for £5,157, not £35

I have been a small-business customer of BT Business mobile since 2007. My usual monthly charge is about £35.

Then nine months ago, out of the blue, I received a text from BT informing me that, owing to “unusually high data usage”, a restriction had been placed on my phone.

I phoned the number given and was told that I owed BT £5,157. Apparently there had been a huge data download of 9.8GB which seemed to have been going on continuously for two days and about which I have absolutely no knowledge.

I have tried every avenue other than the small-claims court to sort this out. NICHOLAS BROWN, EAST SUSSEX

The telecommunications ombudsman concluded that BT had acted entirely correctly. It recommended that BT pay you £30 as a gesture of goodwill.

While the matter was being investigated, BT took the money for the data from your bank account.

My involvement, several months after the incident, led to BT reviewing the case. It said your data limit had been measured and charged correctly. However, it appreciated that you were a valued customer and, as a one-off goodwill gesture, despite the ombudsman’s finding, it has now waived all the excess data charges. You say this makes an enormous difference.

A BT spokesman said: “We’ve changed our processes to try to prevent business mobile customers racking up large bills for data used outside their monthly allowance.”

Now, once any user goes over their data allowance, it adds an additional 500MB of data to the account for £5 and sends warning texts, which include the price of the excess data, and asks the account holder to contact it.

It adds up to 10 such bundles, after which a bar is applied, which means the extra cost would be a maximum of £50. It is then up to the customer to call to remove the bar within the billing cycle. Alternatively, BT will lift the bar once the new one starts. “design issue” rather than a broken pipe, as had been presumed previously.

Fixing design defects is not covered under the policy.

This had come to light just over 10 years after the building’s construction and so fell outside the builder’s own warranty period.

Although not strictly covered by the Esure policy, in recognition that there had been some miscommunication on its part, the insurer was – as a goodwill gesture – offering what it felt was a solution.

This was that its drainage specialists would fit one new valve in the upper bathroom, extending through the bathroom ceiling, and install another valve elsewhere. With building experience of your own, you insisted that the only effective cure would be to dig the pipes up and lay them again.

I took up your case with Esure. After my involvement it offered £4,000 so you could arrange to have the work done yourself. This you have accepted.