Avis Pmb Oribi Airport

I received a car from avis car rental as stipulated by Discovery Insurance for 14 days. During the first 7 days a traffic officer stopped me because the licence disc had expired. Luckily he allowed me to go because I explained it was a rental. I took the vehicle back to Avis Car Rental. They exchanged the vehicle for another that was licensed. The first and second vehicles both did not have floor mats in them. When I picked up the second vehicle I was told it's a straight swop. I was merely given a new set of keys. I asked about new documents, but the person at counter said I merely had to sign I picked it up as it's a straight swop. Inspection sheet was never given to me. The second vehicle was driven exactly as the first. I live on a farm and so without mats in the car there was some dust, but minimal. If they supp**** mats there would be none at all. I went no different places than I had with first car. When I returned the first car there was no issues raised at all about the vehicle. However when I returned the second vehicle today (a day early), Avis car rental pmb turned very nasty. I returned the car at around 16:00. I asked if I must sign anything. The person said 'No, just leave the keys'. I duly did so. Approximately 2 and a half hours later I receive a call from Avis. They claim there is a scratch on the bumper. I inform them I left that car with no scratches on it. The lady became quite nasty over the phone insisting I must return to Pietermaritzburg (I'm now home at Camperdown) and sign the report that there was a scratch. I inform them that I left it in perfect condition with no scratch. I further state that they've had the car over 2 hours from the time I dropped it off and that if there is a scratch that they caused it. The lady will not listen to me. She refuses to send me photographs of the alleged damage. Furthermore she says I must pay for a valet as the car is dirty. The car was not in a bad condition at all. She says there was dirt on the floor. I said it was a mere vacuum if that was even required. She insisted an expensive valet is required. I said fine then I returned it a day early I will come and take it and clean it. She said it was not possible. I asked for a picture of the supposed dirt she was speaking of. She refused to send one. She said if I have a problem I must phone head office.