Damage to bumper query not addressed

Still awaiting Avis's reply - 6 days later. Disgusted: I recently rented a car from Avis. I drove from Cape Town via Wellington to Gansbaai, always within the speed limit and on tarred roads in good condition. However, when I arrived at CTI on Monday morning, your attendant saw a 'dent' on the front bumper which 'could have been caused by a stone'. It was so small, that it was really hard to see the 'damage' with the naked eye. To me it seemed very much like normal wear and tear. I'm quite sure that one would find this kind of 'dent' on most vehicles. This type of normal wear and tear is inevitable. It leads me to think that in theory, any customer could be slapped with a certain amount 'to fix the damage'. That is simply not cricket: Quoting R663 but charging R2218 for 'damages incurred.' The attendant at the airport said there will be an inquiry into my history and they'll be in contact. However, NO ONE made contact - the first wind that I got was when I saw that my credit card was debited by R2218.19. I phoned your offices this morning, and one 'Gift' undertook to send me documentation and/or pictures of the before and after. I've not heard a word.