Reversal of eft declined by onecart

I made an eft to Onecart in error by clicking the incorrect beneficiary 39 Jul R2199.31. I sent daily requests for a refund. On 20 Aug I sent pop and a bank confirmation letter and was told refund to be processed in 5 days. 26 Aug the finance department confirms the payment and says my bank must do the reversal. Which cannot happen as the funds have already cleared .