Avis is *******

I've rent a car from Avis. On collection there were no form to sign on which dents there were, when I asked it was said that everything was marked already. When they collect the car at the pannelbeaters, we went through the car, nothing was wrong and again I asked were do I sign... no you dot not sign anything unless there is damaged to the, so I did not sign anything. Then I got a call stating that there is a dent is the door. The next thing they try to deduct R1777. From my bank account. Again I phoned them, ther reply they will investigate and phone me back. Today I received a final notice to pay R2100 in 7 day!!!!! I gave a car back woth no dent and know I must pay. Where dot these people come from and where do the amounts came from???