PayFast underhanded monthly charge without consent

Back in 2019, CellC owed me a refund for a particular transaction, but my credit card number changed between the date of the original transaction and the date of the refund. CellC must have gone through PayFast to refund me using the old credit card number. R290 has been sitting in a PayFast account with my email address since Nov 2019. PayFast never notified me to let me know there were funds owed to me on their system. Today I get a letter to say I am going to be charged R115 pm for an inactive account. Today's email did not mention that there is an amount of R297 owed to me. It merely states that I will be charged a monthly fee. I promptly looked up this PasFast co. and found a contact number for them. I spoke to a consultant expressing my concern about a future amount being charged to me on a Payment gateway for which I have never registered in the first place. She said she needed my bank details to put on the system. I was very hesitant to give over my bank details as requested. Only then did the consultant inform me that there was an amount due to me on their platform of R297... how ***** that she didn't mention that earlier. She said I wont get my funds unless I give her the bank details. How do I know that I won't be charged a monthly inactivity fee of R115 once they have my bank details. This sounds like a very underhanded way of doing business. Most concerning. I shall avoid ever using this payment gateway if ever I am doing online purchases.