Deposit still not released since 19 March

I rented a vehicle from 19 March until 22 March at King Shaka Int. Since paying with a debit card, they reserved an amount of just over R2000. Since then, after the car was returned, the amount was deducted out of my account. However, to date (24 days) after the vehicle has been returned the reserved amount on my card has not been released. What makes it worse is that this is NOT the first time and I am borderlining on ensuring an investigation from Card Blanche to look into the dealings of cashflow and competency at Avis. Since Avis bills for everything, I will also invoice Avis at my hourly tarriff for repeatedly having to sort out their issues. I truly will never use their horrible service ever again. With Europcar, I have never had a single issue... Only with Avis!