My Subaru Forester was struck from behind by a Mercedes Vito van at an offset angle. Subsequently there was a vibration coming through the transmission. The garage is not prepared to state that the damage caused, which could mean writing off the vehicle, was definitely the cause despite the fact that the car was fine beforehand. It seems clear that a hard knock to a towbar that is fixed directly to the chassis thereby bypassing the crumple zones is very likely to have a damaging effect. What is your opinion / advice please.