I need my refund

I made a booking with online with budget car rental using Rentalcars.com webside and my booking reference number is ***, my confirmation number is ***8ZA1 . I went to pick up the car on 24/12/2019 at 12h00 pm. I was on time and I was told that I cant get the car because I made upfront payment with Debit Card instate of Credit Card. I was advised to cancel the old booking and make a new booking with a totally new payment, which I did on the counter at Budget in Pretoria. I tried to contact Rentalcars.com for cancellation, but their number was not working. I have been charting with Rentalcars.com on their webside demanding my refund but I am not getting any respond, is now 12 days