Not an awful lot. The car is given out of courtesy by the body shop (not from the insurance company) for repairing the vehicle. I can guarantee the repairer will be as unhappy as you, it will be costing them more money to repair your car than they will make as a profit. It is not the insurer's fault the part is not available and needs to be made, there is no provision in your policy for them to provide compensation for non-availability of parts.

You should be thanking the insurer and body shop for dealing with the claim in this way. They could have not authorised repairs, provided a cash in lieu settlement and your daughter would have no car. You may have to realign your expectations. Your daughter is being treated fairly and it is not often I say that about insurers.