Unexplained Reservation

I got a coutersy car through outsurance on contract *** for 30 days and paid my deposit in cash .When the 30 days was up I extended for 3 days from the 11th to 14th Mar on contract *** and an amount of R3000.00 was reserved on my credit card as a deposit. The car was returned on the 14th and It was explained to me that the charge for the 3 days will be debited from the R3000.00 and the balance will be reversed into my credit card balance and obviously the cash deposit will be deposit back into my savings account. My concern is that around midday yesterday another amount of R999.00 was reserved on my credit card .I called Avis Hatfield and Thabo told me the contract for the extension had not been closed yet since they had been off line the entire morning up until at the time I called in to enquire about the extra R999.00.He then told me once the contract is closed off it will take 7 workings days for the R999 to not reflect under amounts awaiting \authorization\" . I'm not happy with the explanation that I got from Thabo because according to the lady who assisted me when I dropped off the car , the money for the 3 days will be debited from the R3000.00. "