No service from Rentalcars.com

On Friday the 6th of March 2020 I booked a car for rental on Rentalcars.com and even made a payment of R665.22 using my capitec gold debit card for the rental before going for collection . My car was due for pick up at OR TAMBO Airport ( First car rental) at 19:30. When I had to make payment for the deposit, the very same gold capitec debit card was rejected, I was told that they don’t accept such cards but from my knowledge capitec and Rentalcars.com have got an agreement that capitec debit cards can be used for car rentals. The lady who was helping me at the counter asked me if I don’t know anyone with a credit/cheque card who can come to the airport to help me out seeing that I needed the car urgently, unfortunately there wasn’t anyone to help. She then asked if the ladies I was with at the airport for collection didn’t have a different card to mine, fortunately one of them had a black capitec debit card, she checked the card number and we were told that the card is acceptable, so now all we needed to do was to transfer the money for deposit from my card to the other lady’s card then we were good to go. As we were busy with the money transfers, the lady helping us from first car rental was busy with the paperwork, she then told us that she couldn’t proceed with the paper work because I was the one who made the booking on Rentalcars.com, therefore the card used for payment should be in my name. She then advised that I call Rentalcars.com to make a cancellation because there was nothing further that she could do. I called Rentalcars and my calls were not answered, i then sent an email (the same Friday night)requesting a refund and making a cancellation, seeing that I didn’t get the services I required or even paid for. Rentalcars only responded to my email on Saturday in the evening saying that i will not be getting my money back because i didn’t make a cancellation on time ( note that I called and they didn’t answer) and that I didn’t have proper documentation(but what I do not understand is that I had my gold debit card with me which they rejected at first car rental but they were willing to take the black debit card that belonged to the lady I was with and in all honesty there is no difference between the two cards ), so to them it is as if I was a ‘no show’. I’m really disappointed and upset about the treatment I got and I want my money back.