The Advertising Standards Authority received 162 complaints about 161 advertisements in the three months since Groupon was referred to the Office of Fair Trading in December over persistently breaking the advertising code for misleading promotions.
In the three months prior to the referral, the ad watchdog received 86 complaints about 77 advertisements.
The ASA began passing complaints to the OFT after finding that Groupon broke advertising codes 48 times in the first 11 months of 2011. Eleven complaints were upheld and 37 were informally resolved.
The ASA said at the time that it had “serious concerns about its ability to adhere to the advertising code”.
The OFT probe is ongoing but possible sanctions include forcing Groupon to change advertising practices. The OFT did not respond to a request for comment.
Complaints have risen with the increase in popularity of the daily deals site, which reported revenues of $506.5m (£319.7m) in the final quarter of 2011, up from $172.2m (£108.7) in the same period in the previous year.
A spokesman for the site says: “The number of complaints to the ASA is tiny in the context of the several million vouchers Groupon has sold in the UK in the period in question, and the many happy customers who return to Groupon again and again.”
He continues: “That said, we are committed to customer satisfaction and take every complaint seriously. Where there have been ASA adjudications against Groupon, we have taken appropriate steps to ensure the issue doesn’t arise again.”