Deals website Groupon is to be investigated by the Office of Fair Trading (OFT), after revelations that the site has breached advertising regulations 48 times in the past year.
The Advertising Standards Authority (ASA) referred the company to the OFT after 11 formal rulings and 37 informal rulings over breaches of the advertising code, the ASA said on Friday.
Groupon offers large discounts on goods and services on a daily basis. Its daily deals on everything from meals to teeth whitening have seen it expand into 16 countries and make headlines around the world - and not always in a positive light.
In November a baker faced closure after a deal offered on the website led to her having to sell more than 100,000 cupcakes at a loss.
Last week the ASA banned a promotion email from Groupon that offered discounts on cosmetic surgery, ruling that it was pressuring customers into making major health decisions in a very short time period.
The online "group buying" model remains in its infancy, and many questions remain over its regulation and standards of business.
The ASA is now referring complaints over the companies "failure to conduct promotions fairly", lack of evidence over whether offers are actually available, and "exaggeration of savings claim".
"Given Groupon's track record, we have serious concerns about its ability to adhere to the Advertising Code," it said in a statement on Friday.
"It is in the public interest that we refer the matter to the OFT, the OFT being better placed to address any underlying issues concerning Groupon's trading practices generally.
A Groupon spokesperson said: “Groupon constantly strives for business practices that are in the best interest of consumers. We are constantly evolving business process to ensure customers receive the best possible experience at the highest standards.
"We are cooperating fully with the OFT to ensure that the rights of consumers are protected.”