Elderly and disabled customers who worry about their heating bills are being exploited by companies using high-pressure sales techniques to sell them 'energy efficient' products.
The Office of Fair Trading (OFT) said that it is worried about the behaviour of double glazing, insulation and solar panels firms, and has written to them asking them to clean up their act or risk being penalised.
In some cases, the OFT warned, salespeople stayed in people's home for around three hours, trying to persuade them to buy products from them. It said this was of particular concern when it happened to elderly customers and others with "obvious vulnerabilities".
Some customers are being told that the products that they are buying will save them unrealistic amounts of energy, while others are not being told that they are eligible for grants or subsidies. The OFT also warned that customers were unaware of their cancellation rights and unclear about paperwork.
"It is important that people can be confident that they companies they deal with are complying with the law," said Nisha Arora, OFT Director. She added that customers needed to be able to make informed purchases "without pressure sales techniques".
The OFT has already taken enforcement action against several energy companies, including solar panel group Solar Technik and Smart Energy.
Audrey Gallacher, director of energy from Government watchdog Consumer Focus, said that some companies' behaviour was "falling way short".
"High pressure sales tactics are the last thing consumers need if they are to make an informed choice before buying double-glazing, insulation and solar panels," she said.
"The OFT is right to be marking the cards of companies who are acting improperly."
The Government is behind a drive to make homes more energy efficient
More customers are expected to invest in energy efficiency measures in the coming years due to the Government's Green Deal which will encourage home owners to take on energy saving home improvements and then pay back the upfront cost through their energy bills.
If the savings are over estimated then these payments may become unaffordable, and customers may struggle to move home as the bill for the improvements stays with the property when you move house, not with the bill payer.