No feedback on unjustified costs

On a recent trip to Cape Town we hired a car from Budget. We paid all in full before we arrived. when we collected the car we were told there was an ±R6 shortage that needed to be paid and they do not take cash, this will be deducted off the reserve put on my credit card. We returned the car full ( the airport in less than 2k's away) and yet we were billed ±R160.00. I tried to call the customer care line and was not successful. I then sent a mail on the 20th December hoping for the 24hr turnaround as stated on the customer care line but did not get an answer, I re-sent the mail again on the 22nd December and then again on the 4th January 2018 and I still have no response. The rental agreement number was ********** 60. I really do hope to get a response now.