General brake question

A good mechanic shop wouldn't have thrown parts at it. They would have done some diagnosis. Can you tell us what diagnosis you did and the results? That might help us narrow down the cause.
No offense to any mechanics on here, but I'm 54 years old and have found only about two "good" mechanics in my life. But I can tell lots of horror stories about "not good" mechanics. There should be a mechanic horror story thread, for people that like to gripe about that sort of thing.