Disappointed service from Avis

I rented a car from Avis in Cape Town, 2 days before it was due, men from tracking department collected the car from my brother who was washing it just because I was not there with him at the time, when he asked them if he can call me in the house they refused and now im getting an invoice of R12 852.12 for me to pay, don't know what is it for and before getting the invoice I went to Avis to report the incident spoke with Rafique promised to get back to me and still waiting.