Charged for avis defective vehicle

I rented a vehicle for a month from the Isando branch on the 8th April 2022. I called the branch on the 13th April 2022 to let them know the car had an issue with vibration at freeway speeds (100kmh). The Avis representative told me that it was normal for the car they had given me. A few days later the boot lock fell out (defective vehicle - no damage) and I again contacted Avis to have the vehicle replaced which I was told I would need to go to OR Tambo to swap the vehicle out. I was told that the car was damaged and that I would be charged for it. I asked to speak to the manager and I spoke to Seakua Kupa who we showed video of the car vibrating and played the call recording of the avis agent saying that it was normal.

I keep calling and getting told someone will call me back but no one ever does.

I have now been charged for the defective boot lock even though it had nothing to do with me. Could the Ramasela Ganda, Dave Porteous please contact me to explain how they charge the customer to repair a defective vehicle with no physical damage?