More than 60 top online retailers have been urged to change their websites after a sweep found that they may not be complying with consumer protection law.
The Office of Fair Trading (OFT) has written to 62 retailers ahead of the Christmas period after a check of 156 websites found problems including unreasonable restrictions on refunds, inadequate contact details and unexpected charges at the point of checkout.
It has declined to name those contacted while it awaits them making the requested changes, said a spokesman.
The sweep to check for potential breaches of Distance Selling Regulations (DSRs) found 33% of sites that provided information on cancellation appeared to impose unreasonable restrictions on refunds, most commonly requiring the product to be in its original packaging or original condition, making it difficult for customers to reasonably inspect the item.
It also revealed that 60% provided a web contact form rather than an email contact address, while 2% provided no electronic contact details at all.
While 60% of sties indicated upfront that compulsory charges would be added to the first price shown, 24% of these added further unexpected charges at the checkout.
However, the OFT also found that the majority of sites were compliant with the DSRs in providing other information, with 99% giving details about delivery times and 95% supplying a full geographical address when payment was required in advance.
Those that do not make the required changes risk formal enforcement action from the OFT or local Trading Standards, the authority said. The OFT has posted a short video on YouTube to help consumers understand their rights when shopping online.
Cavendish Elithorn, senior director of the goods and consumer group at the OFT, said: "The OFT recognises that most businesses want to play fair with their customers and to comply with the law.
"We encourage all online retailers to check their websites so customers can be confident their rights are being respected when they shop online. Businesses can find more information on our online Distance Selling Hub."