Piece of **** car rental place!

There was an additional unauthorised amount of R 3094.95 deducted from my credit card on 24 August 2019. I would like to know why!? I have tried calling the Avis branch which I rented from but no one has been able to assist me. If this is not rectified ASAP I will be disputing this amount with my bank as no one informed of any additional amounts that would be deducted!