No refund after 8 days ( 6 working days)

rented a car from Avis, and returned it on the 08th April , evening, I was told the cameras have already recorded the car is there, the guy checked fuel, it was full, checked car, no dents,.at OR Tambo airport....on the 15 April, still no deposit back (R6000+) I called the call center, I was told it was send through, but she will follow up, I must check my account, same evening( 15 April ) I get another charge of R2078-00 from my card, don't know what is that for....they have about R7500 of my money, and they took another R2078, making it R9500+....the car rental amount should not exceed R1800,...someone please clarify to me what is going on here.