Incorrect billing

I hired a car in September 2019, when I took it back they showed me a cosmetic stretch in the boot that did not even remove the paint, they sent an invoice of R2600 I then requested that they send me an assessment report they failed to send it. 3 months later I get a call from Hybrid collectors I told them that I'm still waiting for assessment report I asked them to send it through 6 months later they sent it and when I reviewed it they charged me for an additional stretch that I did not know. I once again queried the incorrect billing and requested that they review it and bill me correctly 6 months later I'm still waiting for the correct invoice but Hybrid call me every month requesting that I must pay. I don't know what to do anymore. Europcar sent me an sms that I'm blocked to hire a car in any of their branches but they are failing to assist me, this has been going on for 17 months now