repair shop management from owners and managers perspective, and why they won't always take on a job... and how to get around that, if you want to read a lot. I read enough to learn it's in here

 https://www.facebook.com/groups/667188938853705

There's too much to summarize, but basically? Don't tell a shop that the problem, is something anyone else has tried to fix. 

You have the right to remain silent. Do that. 

Problem no one has been able to fix, so you're taking it to this place in hopes they will try? They won't do that if they hear it's already been through other shops, which may have complicated the problem, or, worst case, found that the customer won't pay what it takes, or that the problem is impossible to repair based on parts availability or timeline of how long the vehicle takes up space until parts arrive from supplies with problems. 

Repair shops want easy, simple, straightforward profitable work to roll in, pay up, and go away. Nothing difficult, impossible, or time consuming. Shop management is trained to avoid the less profitable stuff