I'll give you my 2 cents FWIW.
First, have you spoken with the guy who caused the damage? It sounds like you have reliable witnesses, and if he is willing to pay for repairs, one immediate problem is solved.
Second, and this may cost you some money--have the damage inspected by a reputable shipwright or surveyor. This will help you in any discussions with the guy who caused the damage; or in discussions with the insurance company.
Third, if we are talking about 2 one foot long scratches, have you considered doing the work yourself; or having a knowledgeable friend do it?
Fourthly, while it doesn't help you in this case, you may want to look at a new insurance company when renewal time comes up. I googled Premium Marine easy enough, but they are not members of the Marine Trades Association. When we completed the purchase of our boat, our broker strongly urged us to deal insurance folks who understood recreational boating and the marine industry. It was good advice.
Finally, what marina was this at? I was going to make a smart aleck remark about how we all should keep an eye out for that guy. However, most marinas really want to know about problem boaters like that. If this guy has already had problems, a complaint from you may encourage the marina to get the guy to move on--just don't send him to Port Moody!