A frail pensioner was reduced to tears after British Gas got her meter readings wrong - for four years.

Widow Joanna Mason, 84, was threatened with court action and made ill by the power giant, which claimed she built up more than £800 of arrears.

In reality the "debt" was because it had overestimated her electricity use in 2004 and failed to notice the mistake.

Mrs Mason continued paying a direct debit for the correct amount - £28.50 - and so quickly fell behind. Mrs Mason said she was reduced to a wreck by the thought of bailiffs hammering on her door in New Church Road, Hove, even though she had done nothing wrong.

She told The Argus: "I had visions of them bashing through the door to come and drag me out on to the street and then take all my possessions.

"I rescue dogs and I was told they may have to take those away to pay the bills. I said over my dead body they will."

Mrs Mason, whose husband died in 1994 and who lives on a state pension, was so worried about the situation she even borrowed £1,500 from a relative in the US.

She said: "I couldn't sleep. I don't use much electricity at all. I have no electric cooker, I have a vacuum cleaner, a TV, a one-bar fire and a small heater in my bedroom, but that's it.

"I knew they were wrong but every time I tried to contact British Gas they told me I was the one in the wrong and would have to pay."

Following an investigation, British Gas has acknowledged its error and apologised.

It sent Mrs Mason a handwritten note confirming the mistake, along with a bouquet of flowers.

A British Gas spokesman said: "We are very sorry for the error and have written to Mrs Mason about the issue to clarify things.

"Our staff looked into this as a matter of urgency once it had been highlighted."

Mrs Mason has now had her electricity bill reduced by the firm but claims other pensioners could find themselves in a similar position.

She said: "I'm relatively fit for my age and was just about able to cope but others won't be able to. It could kill them."

Other pensioners rallied around Mrs Mason, offering support. She said: "I was so grateful."

Hove MP Celia Barlow, who helped start the investigation, said: "This was a worrying error by British Gas, especially when you think of the not inconsiderable number of older, vulnerable people living in Hove and Portslade."