Traders may be misleading consumers by not making it clear they have signed up to regular card payments, or that these can be cancelled, the Office of Fair Trading says.
Asos customers were left enraged after a code giving up to 40% off was pulled early, though the fashion firm is giving let-down buyers a new deal in return.
Thousands of disappointed Boots customers were told they'd won a luxury trip to Barcelona — only to be told later the chemist had made a huge gaffe by emailing all entrants to say they were successful.
Thousands of Comet customers have been left worried where they stand after the store went into administration, but many consumers have a legal right to get their money back if they've lost out.
Comet has launched an in-store liquidation sale as administrators close down the failed electrical chain, but the offers are more standard sale than fire sale.