Dieter, I think you need some serious help.
If I was you I would contact Colin Ferns (see info at the link below). I don't know how far you are from him, it might be in your best interest to get a hold of him.
Again, if I was you, I would have my car towed to his shop so he may prepare and issue a final report that you then present in a court of law. Once you get your money back from the previous shop you can use it to have Colin and his team do a proper job for you. Sorry to hear you had to go thru this type of aggravation.
http://www.colinferns.comPS. I guess we all learn sooner or later. A while back I ordered the little chrome ring that fits around the ignition key in our dash, I paid $49- plus $10- and $22.30 for that little sucker. When I got it zi fond a used one all pitted for my money. Last month I phoned the Classic Centre in California ordering some control arm rubber bushings. I ask about this ring and got a brand new one for $17.50 ... yes we all have to learn.