they messed up my car

I was involved in accident which resulted in my car having to be taken to Panel beaters, Discovery insure organised CarWorld panel beaters to fix my car, then I drove my to them and went tofetch a courtesy car that DDiscovery had organised for with Avis, on the 22 of October I received an SMS from Avis that I mustreturn the rented car because my car has been repaired, it turns out my car is not finished and they canceled my contract with Avis without even letting me know what's going on, when I call them I been sent from pillar to post and no one has the answer as to what is happening with my car, firstly why would I get an SMS from Avis before Discovery notifies me that my car us ready, Avis has resulted in taking a huge amount of money from account without my Authority, I never gave them them my banking details or any signature saying that they can do so, Carwworld won't Answer my calls and when they do they tell me that my car won't start, it perfectly fine when I drove it to them, why would they lie and tell discovery that my car is ready when they know its not, I feel like I am being ****med, discovery won't answe me and no one knows what's going on.