How do i report trademark infringement?

[ictbillet_com]

Hi, I can not find an email address to forward information on a fraudulent seller.  He is using trademarked GM logos in his photos.  I spoke with our Licensing manager and he said this guy is definitely not autherized to used their logos.  It is disappointing to us sellers that actually pay good money to legally license logos, then someone bootlegs them and undercuts us.   Any help would be appreciated.