Four of the biggest group discount websites have been given a warning after the Advertising Standards Agency said it is concerned over the rise in complaints about their deals.

BBC News reports that Groupon, LivingSocial, kgbdeals and Wowcher have all been reported to the ASA multiple times. In the first nine months of 2012, 391 complaints against the aforementioned four websites were received, compared to 244 for the same period last year.

The top offender, Groupon, should especially be feeling the heat, as the website has been under strenuous watch since last year from both the ASA and the Office of Fair Trading, who found that the company was not adhering to consumer protection regulations. Aside from that, Groupon has been under fire for the same length of time for having an “unsustainable business model”.

The ASA has stated that continual breaches will result in further action and possibly fines.