If your parent company has sent people to this guy before, they'll probably already know. Keep your footprint small in a professional work setting, in specialised fields everybody knows everybody else and there will be bonds there you will not be aware of. People are animals, man, it doesn't matter if you are in the right, it only matters who has control. Without knowing the nature of the relationship between your parent company boss and this guy, you just open yourself to luck by complaining about him.
Before you instigate anything when it comes to people, know the terrain. If it's a guy you'll never see again, that's party time. Scrap all you want, fill his head in, go your merry way. Work setting, neighbourhood, essentially repeated contact or influence with the same people, you have to plan it with the head first, your righteous anger second.
8 weeks, smile, get out.