Inconvenience by discovery sure

On the 28th June 2018 I was involved in a car accident. The insurer has a contract with car world to fix the car. Car world was given authority to fix my car after two weeks,when I inquired with the insurance they said it's because of parts that were not available,this cost me to have the hired car kept and extra two weeks. When I inquired with car world they did not agree with what discovery insure claimed,delay was from them as the gave authorisation late. I'm now sitting with Avis bill because of their incompétence. As to make it worse they only gave authorisation to fix part of the problem which was cheap and the bulk they left and not gave authorisation to be fixed. This cost me money as it created further problems on the car,in October I had an alternator problem which was due to the accident and they can confirm that,they never fixed it. The alternator was completely burned. IAM paying insurance and yet I'm left with such debt and inconvenience. It such a pity I changed insurance to them to get ****** like this,when I was with budget I never experienced such.