Almost nine million households, equalling 34 per cent, have been billed inaccurately by their energy supplier at least once in the past two years. Nearly one in five respondents (19 per cent) said they had been sent an inaccurate bill on more than one occasion.

When asked how long it took their energy companies to resolve the issue to their satisfaction, 13 per cent of respondents said just one day, 25 per cent said up to a week, and a further 27 per cent said eight to 28 days. However, on average, the time taken to sort out incorrect bills was just over two months.

For uSwitch, the energy industry’s outdated metre technology is at the root of the suppliers’ inaccuracies. Although two thirds of all energy customers had their metres read in the last six months, many of them fall foul of the difference between the previous estimated readings and the actual reading.

In addition, energy usage differs throughout the year, with most households using more in the winter than in the summer, which complicates the matter even further.

Overall, payments matched usage on just over a quarter (26 per cent) of gas and electricity bills, while 40 per cent of customers were owed money and a further 26 per cent were in debt to their supplier.

For more than 11 million consumers (43 per cent) the discrepancy between estimated and actual reading resulted in a costly surprise: on average customers were £137 in the red to their energy companies, while one in ten ended up owing between £201 and £500.

“I suspect that suppliers will continue to be haunted by this reputation for inaccurate bills until smart metres finally lay that ghost to rest – unfortunately that won’t be for many years,“ Ann Robinson, director of consumer policy at uSwitch.com, commented on the survey results.

“In the meantime, suppliers are trying to work with their customers to resolve the issues and tackle the root cause – discrepancies between estimated and actual readings – which can often leave households unexpectedly out of pocket.

“Suppliers are making it easier than ever for customers to read and supply their own meter readings and in some cases are even rewarding those who do so.”

She recommends that: “Whether there is a reward or not, I would still urge consumers to respond to metre reading requests or to supply their own readings. Relying on estimates is never a good idea as you could end up in debt or struggling with an unexpected bill.”

In times of rising energy costs it is all the more crucial to keep an eye on your gas and electricity bills and to ensure that your bills are correct. With an increasing number of energy deals on the market it is also always worth shopping around for the best offer. Compare gas and electricity prices from different companies and you may find that switching to another provider could save you hundreds of pounds.

©Fair Investment Company Ltd