my suggestion is: call the insurance company and the repairing garage peple once, give  them a warning for the delay of over 1 month! and also warn them that the matter would be reported to the Police, and to the court if required. Let the professionals take care of the problem.

Enven better, if you can directly go and meet them. Remember, talk as if you are really serious and show some taunting/angry serious looks on them, else these people will not heed to you. I have been thru the same fate as you long time back. I was lucky I had a second car, so I could drive to the garage and give them the warning of report of police...got my car back in 3 days!