Janice Brogden did not receive an accurate bill for five years

Energywatch North West says it receives about 400 calls a week from worried customers.

The group found that about 798,000 of 3.8m homes in the region had incorrectly estimated bills last year.

Energy firms say that problems are often caused when their customers fail to notify them about changes in circumstances which affect the bills.

Problems reported have included bills totalling �1,800 and demands for money sent to addresses which do not use gas.

'Customer responsibility'

Janice Brogden, who runs the Derby Arms pub in Ormskirk, Lancashire, did not receive an accurate estimated electricity bill for five years from Scottish Power.

She said: "Despite me disputing the bill, they sent representatives around to disconnect me.

"It only stopped because of the state I got myself into."

Scottish Power says it had the Derby Arms registered as vacant and it was during an investigation into empty properties that it discovered it was occupied.

A spokeswoman said: "When a customer moves into a new home or business, it is their responsibility to ensure that they register with the electricity company. This had not been done.

'Frustrated'

"If a customer has not received a power bill for some time - in this case it was more than four years - this is something that should send alarm bells ringing and they should contact us as soon as possible."

Teresa Dillon, from Blackley, Manchester, received a bill for �1,800 from British Gas even though she uses only electric appliances in her home.

Ms Dillon said: "Customers are paying for this sort of stress and the companies are failing them. I wish more people would complain to Energywatch and then the firms might actually listen."

A spokesman for British Gas told BBC News Online that it plans to remove the meter from Ms Dillon's home and has sent out a letter to her confirming that she owes nothing.

Energywatch, which deals with 400 calls a week about bills, is advising customers to check their paperwork and give energy firms an accurate meter reading.

It also says customers must notify their supplier if they do not receive a bill.

Director of Energywatch North West, David Sidebottom, said: "This year, Energywatch North West has seen consumers wait years for a bill, be confused by bills, distressed by bills and frustrated by bills.

"Energywatch wants to see bills that are accurate, clear and on time."