CA Bureau of Auto Repair has some strict rules. Unless you signed something saying you were giving them a non-refundable deposit, you can get it back.
I filed against a local company once and got money back for work that was done, but not estimated and agreed to.
On this site is a Complaint button:
I know it says smog check, that is the biggest current issue. But it is for any automotive repair station complaints.
Just be honest with the facts, don't try to embellish. If possible furnish copies of any and all work orders, estimates, etc.