How long does it take?!?

About5 weeks ago I logged a claim for a minor accident. In total it almost 3 weeks just to finalise/approve the claim. My car has been at the body shop for 2 weeks and no repairs have started as yet, because they are still waiting for parts. My issue is the fact that I have 30 days car rental on my policy (which I pay for every month) and 75% of that time was used just to approve the claim. If I knew Auto & General takes this long just to approve a claim, I would have taken the 60 day rental option. I was informed that the rental has to go back on Monday, 8 June, but they haven't even started working on my car. I was explained that if parts are on back-order they cannot extend the car rental, but... POINT1: Maybe if it didn't take 3 weeks just to approve the claim, there would have been stock of the specific part. POINT 2: I asked them to please let me know what part they are waiting for because I know many people in the car parts industry and maybe I can locate the part earlier. I was promised that they will mail met the part details, but nothing as yet... This was 5 days ago. How can I accept this. I have professional career and in 3 days I have no car!!!!