Pensioner Pamela Fowler was incredulous when an electricity bill for more than £47,000 landed on her doormat.

The 72-year-old has no idea how Seeboard Energy came up with the figure and spent sleepless nights wondering where she would find the money.

She said: "When I opened the bill I thought I was seeing things. I thought I would sit down and have another look at it but it was still this horrifying amount.

"I live alone so I could not see by any stretch of the imagination how I could have used that much. I was away for Christmas and give my readings every three months."

Mrs Fowler, of Tower Road, Lancing, who works for a double glazing company, has paid her bills by direct debit for 15 years.

After receiving the giant demand the mother of eight telephoned Seeboard but couldn't get through to an operator. She contacted Energywatch South, which promised to fight her case.

The £47,000 bill was retracted yesterday after Mrs Fowler travelled to London to help Energywatch present "a super-complaint" - an accumulation of several complaints from customers - to energy regulator Ofgem.

Apology She was given a bouquet of pink and purple hyacinths by Seeboard chief operating officer Derek Lickorish, who publicly apologised to her on BBC Radio Five Live.

She said receiving the bill had taken years off her life.

She said: "I am very pleased with the outcome but it still doesn't account for the nights I spent worrying about how I would find the money. I am lucky I don't suffer from heart problems otherwise I might not be here today.

"I was going through a living nightmare. Every time the phone rung I thought it might be the electricity board giving me bad news, saying something has gone drastically wrong."

Seeboard has also written off an outstanding £600 Mrs Fowler discovered she owed when she realised her direct debits had not been taken for the last 18 months.

She said: "I must admit I don't check my direct debits because I thought they could not be stopped unless I cancelled them.

"They said they would pay off the bill because it was their fault the money hadn't been taken. Now I have a clean slate."

Mr Lickorish said: "Seeboard Energy apologises unreservedly to Mrs Fowler. Human error has let us down on this occasion and we regret any upset this has caused.

"We are now reviewing our procedures to ensure this does not happen again.

"Any error is unsatisfactory and the highest standard of customer service is our number one priority.

"Our volume of Energywatch complaints is equal to only one in every 25,000 customers and we are continually well below the industry average."

This is not the first billing problem Mrs Fowler has faced. When her children lived at home, the family received an unusually high bill. Engineers eventually found her house had been supplying a block of four flats with electricity.

She said: "The wires were so hot from all the electricity flowing through them they had melted.

"At the time I didn't think much of it. I thought it was because I had children and they were using a lot of electricity."

Energywatch hopes the super-complaint, the first ever in the energy sector, will prompt a radical overhaul of the billing process.

The watchdog received 40,000 complaints to its billing helpline last year.

Hazel Parsons, of Energywatch South, said: "The super-complaint is a new measure only certain bodies have the power to use. It makes sure the complaint gets fast-tracked and ensures what you say gets listened to."

Failure to deliver bills, calculate them correctly or ignore metre readings and rely on estimates are among complaints due to be investigated.

Complex bills which make it hard for customers to understand charges or work out if switching supplier would be more economical have also come under fire.

Ofgem has 90 days to consider the complaint. Possible outcomes include a referral to the competition commission, a market study or enforcement.