People still seem to be forgetting it was the OPs sister who damaged someone elses car. All this "tell him to do one" or "tell him you'll polish it out" "try and do him over" stuff is hilarious.
It's not the OPs decision to make! The third party (Mr Saxo) is FULLY in control of the situation because HE is the one who's had his property damaged! You lose the rights to call the shots when you damage something belonging to another person.
It would be lovely if he was being really easy going about it, but he isn't, and he doesn't have to be - life is annoying like that.