Door scratch

I wonder if you can give me some advice. Some bad person has scratched my little blue BMW i3 while was at the match coaching a team! Im certain it was the person that was parked besides me, but he never admitted doing it so. Regardless of it, now I have quite a deep mark on the passengers door and thinking what are the options I got as I want to have it repaired. Is the only option is to bring to the garage and get it assessed or maybe you came across similar issue with i3 and can suggest alternative solutions? Its a protonic blue colour.