AVIS CAR HIRE ARE *******!!!

I rented an Avis car for the 100th in Johannesburg on the 11th of August 2017 and returned the car on the same day. On returning the car I inspected with an Avis employee to verify that all was in order ie. Tank was full and no damage to the car. Avis than bills me R3510. 64 on that same day which I hadn't noticed until now. What's even more scary is that even made no contact with me but instead went ahead and billed my credit card whilst I am completely unaware. I really don't understand what's gone wrong here but it seems like Avis are thieving bunch of ******s. To every single person who reads my review, PLEASE BE AWARE OF WHAT AVIS IS DOING AND IF YOU CAN USE OTHER SERVICE PROVIDERS BECAUSE AVIS IS NOT TRUSTWORTHY. THE WILL ***** FROM YOU WITHOUT YOUR KNOWLEDGE.