AVIS CPT charge me for damages already on the car!

I arrived in Cape Town AVIS to collect my rental car. The original form says the car has no damages marked on the car. When I got to the car there were many scratches and dents not marked. I called over the official to help me mark the damages on the form before taking the car, but instead of him making use of the diagram to mark the damages, he writes some meaningless abbreviations on the top of the form like R/W and S/P etc...At the time, I didn't think anything of this, however upon returning the car another official points out that I scratched the front bumper which I refused to sign for since the original damages had not been marked properly on the form with the abbreviations. 2 weeks later I get debited 4k on my credit card without even receiving an invoice or quotes for the damages and now apparently I also dented the back door. After many phone calls later, I manage to get the invoice, quotes as well as the document showing the damages after returning the car that I now have to pay for, only to find that I had taken pictures of these dents before I drove the car... Now I am trying to get my money back while I pay for the interest on my credit card 6 weeks later... Pathetic!