figaro

Ring them up, explain to them that you brought a perfect running bike to them and now it's fuc'd since their mechanic touched it. Tell them you want it put back to how it was at their expense. If they say no, tell them you'll be taking them to court. Let them know that you'll also be billing them for your travelling expenses too, seeing as the bike is your only transport.

If you can afford it, take it to another mechanic and explain what's happened, then get them to give you a written quote for the repairs needed to rectify the other guy's mistakes.

And do please chase the garage for the cost of the repair. They get let off far too easily, far too often. My mate got stung nearly a grand for new throttle bodies at a Triumph dealership in Northants. I'd already told him to try a new O2 sensor first but he stuck it in the garage. The bike came out just as bad but with him out of pocket to boot, I put a new O2 sensor in and it runs perfectly. He never chased the garage for that grand.