They damaged our new car installing the base plate

I think the OP is lucky the RV place was honest about the situation....to many places (RV or Automotive or Towing company or anyone else hwo might have had a customers vehicle for some reason) would have patched that line up with a chunk of hose over the hole and never told the customer a thing about it....people outside the service and repair industry have very little idea what unreported damage and half baked repairs are done every day....