Mango refunds department very poor customer service

I made a booking on the website on the 23rd of March for flights to Durban and back on 29 and 30 March. As part of the booking, I used the option to pay with my credit card, which went through, and received the necessary tax invoice, confirming payment and booking details.

Upon arrival at the airport on the 29th, I was advised that payment was not received for the booking and I had to make payment again at the ticket counter. I was advised I can contact the refunds department for a refund on the first payment.

I have made contact with the refund department on several occasions, was (incorrectly) advised that I should follow up with my bank, did that without success.

It has been weeks since I have requested the refund, meanwhile Mango is sitting with thousands of rands for flights that I paid for twice.