Hertz doesn't unblock the money on your credit card in 9 days after return of vehicle

On 01.02.19 I picked up the vehicle I hired at Hertz Kruger Mpumalanga Airport and dropped it off again on 03.02.19. Never before or on the day of pick up or delivery do they mention how long they take to release the block on your credit card. The first time I called the lady from Head office said that it takes 21 days to get your money unblocked. I was not happy with that so I called the Hertz Kruger Mpumalanga Airport, where that lady told me it takes 7 working days. On 12.02.19 the 7 days has passed and still the money was blocked, I called again on 13.02.19 where the lady told me that she will talk to the manager and arrange to unblock. So now today I have waited 9 working days. Do I have to call them every day? This is poor service because I have to bring the vehicle back on a specific time and date and then they can keep my money as long as they want to, this is not fair at all.