E*** - AVIS Renting

I rented a car on 25 November 2020. Handed the car back on 08 December 2020. For this 12 days I only drove the car 3 days, the rest of the time it was parked. Handed the car in and they picked up a damage spot on the bumper, not in sight under where mud guards usually is. Took a photo, on the photo you can see it is an old mark already patched up. They said I still have to fill in an accident report. Car went in for the inspection and quote, call me back and ask if I have drove in hail. I said NO, they must not start. I battle a month to get the quote after they say I must pay R2954.35 excl vat. Receive the quote, there is n f/bumper and r/bumper cost for me! WHY? Still haven't heard back from them. Why must I pay for someone else damage. Both the bumpers where fixed with white paint or something! Now you want me to pay for the previous renter damage. This is not acceptable. You already took my deposit of R1500.00 my cost where only R436.96. Your amount for damage on the invoice is not the same as on the quote from the panel beaters. Please explain this?