AVIS MONEY *****

I have rented a vehicle from AVIS from JAN 2018 until 4 MAY 2018.I have had problems with amounts of money that Avis has blocked off on my account but never ordered. Also i waited months for my deposits to be reimburst to me. The final straw came when i have ended my bussiness with them on 4 May 2018.I returned the car (with a little bumper damage for which i received a qoute of R3700 that I have to pay by the end of this month). At 00h00 on 15 May 2018 an EFT transaction was made from my account to AVIS .The amount was for R10176 with a reference of CAR PURCHASE. AVIS in Strand has not been very helpfull and cannot tell me why an unauthorised transaction was done without my knowledge.This smells like ***** and I cannot seem to get them to Reimburse me.