Not responding to clients call

I rented a car at OR Tambo on 22/12/15 to 5/1/16 and drove to ECape at PE the car was flushing warning lights and the was a funny sound,i drove to their PE branch .They told me i was not supposed not to be given that car In the first place as it was due for service. They gave me another car,and we checked for damages of problem car using their DAMAGE CHECK SHEET 380360 .i was told to write a report and did that . and handed in and left.It is now 23days they a not refunding the holding fee of my credit card .I have been calling every 2days and i am always promissed the will solve my problem but nothing is happening is this how Bidvest car rental work ? PROBLEM CARS AND NOT RELEASING HOLDIND FEES. I AM STILL WAITING TO HEAR FROM THEM.