MORE than 500,000 energy customers are having to wait more than six months to resolve problems with their bills, according to new research.

And in the past two years about 8.2m customers have been billed incorrectly, according to the comparison firm Uswitch.

Of these, about 7% have had to wait between six months and three years – or even longer – for their disputes to be resolved.

Uswitch also estimates that as many as 10.4m customers have unexpectedly found they owed money to their energy suppliers following inaccurate estimates, adding up to £134 to their bill, or £1.4 billion in aggregate.

“No other industry operates such a hit-and-miss approach,” said Tim Wolfenden, an energy expert at Uswitch.

The news follows last week’s price rises by British Gas and EDF. Around 13m British Gas customers saw their prices rise by 15% for both gas and electricity, bringing the average dual-fuel bill to £1,051.

Some regions have seen steeper rises for electricity. North Wales customers, for example, had bills increase by 19%. Unlike Npower, however, it has decided not to introduce regional variations for gas.

EDF, the fifth-largest supplier of gas and electricity, also hiked rates for its 5.5m customers who saw their standard gas bills go up 13% on Friday, while electricity rose by an average of 8%. Dual-fuel bills rose 11%.

British Gas was the third supplier to announce higher standard tariffs this month. Npower increased electricity bills by an average of 13% while gas bills rose by 17% on average.

As bills go up, however, the customer has seen no improvement in services. Complaints have nearly doubled in the past two years, with British Gas the biggest culprit, according to Energywatch, the industry watchdog.

In the past 12 months Energywatch has won £7.4m for consumers in the form of lower bills and compensation – an average of £119 for every complaint.

The Energy Supply Ombudsman – a separate body that has the power to force suppliers to pay compensation of up to £5,000 to a successful complainant – said that other gripes related to poor service and switching problems.

It has recently cut the time before it will act on behalf of customers from 12 weeks to eight. However, there is no requirement for suppliers to log complaints.

One reader, Anne Bellis, 53, from Goole, East Yorkshire, said she had been without an official energy supplier for more than a year. British Gas, is in dispute with Npower over who should supply her.

“I was sent a letter by British Gas in January last year saying they were sorry I was leaving them for Npower,” Bellis said. “This was a shock as we never decided to switch. Since then, we’ve not received an energy bill from either supplier.”

She received a letter from British Gas last November, promising to resolve the matter by December. She is still waiting.

And David Buckey, 38, from Rochdale, Greater Manchester, was unable to get British Gas to send him a bill for almost a year, despite repeated requests.

After about 12 months, he was sent a bill for £1,000 and assured that the problem would not occur again. Six months later, he received a bill for £500. He has now moved to Scottish Power.

Another reader, Patricia Burnett, 75, from St Leonards-on-sea, East Sussex, signed up to British Gas in February last year after agreeing a monthly direct-debit bill £15 for electricity and £20 for gas.

Though she was receiving gas bills regularly, her electricity bills were less regular – she received only two over the course of last year. She did contact customer services who told her that she owed £94. “This seemed very odd to me as I didn’t think I owed that much.” A few months later, she was sent a bill for £286. Burnett refused to pay and, after complaining, received an amended bill of £12.80.

The regulator, Ofgem, is drawing up a suppliers’ code for handling complaints in the next few weeks. It is expected to include a requirement that firms log disputes when they start. “At the moment, companies have their own procedures, but we’re hoping this document will create an industrywide standard,” it said.

In the meantime, verbal complaints should be followed up with an e-mail or letter to establish a record of when the supplier started trying to sort out the problem. The ombudsman can accept this as evidence that eight weeks have passed.

If you are not happy with the supplier’s response, go to energy-watch.org.uk. If the dispute concerns bills or switching suppliers, contact the Energy Supply Ombudsman on 0845 055 0760 after the eight-week deadline.

The Sunday Times will be putting together a manifesto for energy companies to demand action on behalf of their customers, so let us know about your problems.

HOW TO COMPLAIN

IF YOU are having trouble with your supplier, first contact it about your problem. Follow this up with a letter or e-mail to ensure it registers when you made the initial complaint.

If the problem is not resolved within a week, contact the supplier again. If you feel you are not being treated fairly, you can get support from Energywatch, which can be contacted through the website www.energywatch.org.uk.

If after eight weeks your problem persists, you can contact the Energy Supply Ombudsman who will act on your behalf. The contact number is 0845 055 0760. You can also try the website www.energy-ombudsman.org.uk for further advice.

If you are consistently being overcharged, make your own meter reading and inform your supplier either over the phone or through its website.