Have it done properly elsewhere and send them the bill. No point in going back and letting them make everything worse.
Used to go to a shop that I paid $10 to have them change the oil for me provided I bring all the stuff needed. I eventually got new tires and needed an alignment so I go to them. Make a left hand turn and the tires squeal. Went back to them and they said sorry we don't have the right specs. They returned me the money so I went someplace else. At least they were honest in that aspect. Hopefully yours is too.
Unless you're just having too much fun with them...