Refusal by Capitec to refund a transaction that was unsuccessful

On the 9th of April, I used my Capitec app to transfer money into my FNB account, the transfer was unsuccessful. On the 10th of April, I called Capitec asking them to refund the money, it was an amount of R6000. Capitec informed me that they are aware that the transaction was not successful but they will refund me, It has been 3 days now and every time I call them, they keep promising to refund me but they are failing. I know with other banks such as FNB within 24 hours the reversal is done. The case number is opened however it seems like its a struggle to get this reversal done. I have to use the money urgently for my personal responsibilities but they are holding on to it. FNB confirmed that they did not receive the payment and Capitec agreed that the transaction was unsuccessful but Capitec is not refunding my money. It is now a case.