I’ve been through small claims to get money back on a bad spray job I had done on a vespa I restored.
The threat of court got money out of the guy but it was stressful and dragged on. Could easily have cost more than I would have gained.
You need to do letters etc to the people responsible, failing all that you have to go to mediation to try get it resolved that way, even so I couldn’t find a mediator for civil disputes and even if i did it would be costly to use them. Failing that you then go to court.
I was lucky that the guy folded and it didn’t cost any more than a few recorded letters.
For the sake of a dent in a door I would just put a sticker over it. I only carried on with mine as the sprayer ruined a huge amount of time and effort on a restoration I was aiming to make concourse and I paid £800 for his super shoddy work. I wouldn’t bother if it was significantly less tbh.
Otherwise call citizens advice for some ideas, they were actually pretty good.
Ive got a vespa for sale if anyone’s interested...