AVIS charge exhorbitant fee with alleged damages (3 small stone chips)

I rented a car from Avis Cape Town International Airport on 1st January 2025. I was told the car had been checked, when I got to the car there were no Avis personal in sight, we checked the car noticed normal wear and tear and drove off. I returned the car on 10th January, to be told that we had damaged the bumper, 3 small stone chips and they would investigate. I then got an email to say that we were liable for the damages and they were going to charge us. 2 days later i got an sms to say the amount was R1810.87 for damage repaired to the bumper. The bumper has alot of stone chips, the 3 they are claiming we did represent about 5% of the bumper surface area and yet we were charged to respray the whole bumper. To date i have not been satisfatorily answered on my questions I have asked and I am now being ignored. I will never rent from AVIS again.