AVIS JUST TAKING MY MONEY

I have such a bad experience with Avis car rental. I rented a vehicle at Lanseria Airport and received a Hyundai I 10, On my way to Welkom with my wife and 1 year old girl in the car, the air- con did not work in the car and the cluch had such a bad shudder that I though it will brake at any moment. Once I got to Welkom I phoned Avis to ask if we can shop the car because of the faults they said it was ok. I changed the car at Welkom branch and we checked the car that everything is in order with the lady that brought the car out for me. I drove straight from Avis Welkom to Avis Lanseria, when I returned the vehicle myself and a gentleman from Avis Inspected the vehicle on return, Everythink was ok and there were no damage seen on the car. One week later Avis deducts R3080 of my bank account on top of the rental and service costs. I phoned Avis call centre to find out what the amount was and they could tell me immediately, and said they will get back to me. I got an email to say that it was a damage windscreen on the vehicle and thats why they deducted the amount. After many calls to Avis an plenty of emails they cant give me the proof of the checklist where we inspected the vehicle for damage. Avis just claims that there were no previous damage to the vehicle noted so I stay responsible for the damage. How can I be responsible if we inspected the vehicle before we rented the car and when we returned the vehicle. I would have seen if there were a broken windscreen on the car. AVIS THIS IS JUST WRONG!!!! we dont have the money just to throw away and that for something I know was not true. Your'e logo says we try harder, Well sorry but nobody even tried solving my problem.