[bell]

In ohio when my 911 was smashed I had a rental, the repair extended past 2 months, after the first 6 weeks I was told I had to turn in the rental, after some discussion as to the legnth of time for the repair it came down to "if" the car is not finished being repaired then they will pay, but needs to be "filed" by the repair facility......basically the shop needs to contact whoever is paying and tell them it's not done and get your rental period extended.....however he will get charged for it in most cases, cutting into his profit.
if you didn't sign off on your car then technically it's not done.......
Personally I would try to leave the shop out of it, and deal directly with the insurance company.....this is all based on what exactly wasn't done correctly or as the insurance companies call it "pre-accident condition".......