ACCC investigating outdoor advertising companies

It has been reported that the ACCC is investigating alleged exclusive dealing conduct (rebates) in the outdoor advertising industry. Needless to say, it is very strange for the ACCC to clear a couple of major mergers in an industry and then almost immediately commence an investigation into alleged exclusive dealing in that industry.
If the ACCC had been aware of the alleged rebates when they cleared the mergers, they must have concluded that these agreements did not substantially lessen competition. So why the investigation? However, on looking at the Statement of Issues re the APN Outdoors - oOh!media merger and the media releases in the subsequent Adshel and JCDecaux matters there is no reference to the payment of rebates. It may be that the ACCC was unaware of the alleged payment of rebates in the outdoor advertising industry when it cleared the earlier mergers.

http://www.adnews.com.au/news/rebates-ratbags-and-complaints-execs-weigh-in-on-accc-crisis-for-ooh