"Ding up" is a phrasal verb. But it is informal. In addition to what Peachey said, the "you" in the sentence could refer to "your car" or "your scooter," etc., if your vehicle had been in an accident.

A "ding" is a dent. To "ding up" something is to make many dents in it. In the case of a person it means to beat them up.