According to Australian media news site Mumbrella, discrepancies in reporting emerged around four months ago, leading to a number of staff leaving the company. The investigation was initiated by Mediacom itself once it learned of the problems, and was carried out by EY.

It found that after some campaigns, for Foxtel, IAG and Yum! Brands (owners of KFC and Pizza Hut) had ended, employees altered the original demographic audience targets to make it appear as though the campaigns had reached the official OzTam audience ratings numbers.

The investigation also revealed that Mediacom had breached the policy of its own parent company, GroupM, by selling back to clients free or heavily discounted advertising time given to it by TV stations.

“This incident has had a devastating impact on our business, on me personally, on Pej [Mediacom CEO Mark Pejic] personally and on a number of other people in the organisation,” said GroupM chairman John Steedman.

“I have never seen anything of this magnitude happen to me personally and so it has been incredibly difficult and stressful to deal with, but we have managed our way through it.”