I have a 2002 supercharged V6 Monaro. Pity Holden chose to get cheap Chinese "leather" for the upholstery. Mine is split everywhere necessitating very expensive repairs. Everyone I know who owns or has owned one has the same problem. Further, very few mechanics have a clue how to service one of these cars. They know nothing about the supercharger and can't even seem to do a simple decompression test. I have had my car serviced regularly and it started to make a bad noise in the motor, which I thought was probably a cylinder. I took it to Kmart and the manager told me it required new engine mountings, which they did. I drove the car straight after their repairs and i t blew up late at night in the rain on the freeway, necessitating a complete engine recondition. This cost me all up $8500. The crook cylinder had fallen into the motor, thereby causing major crankshaft damage. Despite of all my attempts to get reparation, Kmart doesn't want to know about it. The state supervisor kept telling my solicitor he would get back to him, but never did.
Your complaint is with the mechanic who did the repairs, and you should pursue it through legal means, which appears to be what you are doing.