FNB unable to reverse funds that never reached the Supplier via Speeadpoint

I swiped my cheque card at a supermarket and the speed point declined. However I got an SMS on my phone that the payment went through. The supermarket did their best to prove that the payment was not received on their side including banking all transactions from that speed point, all in an effort to prove that the payment was unsuccessful. I them phone FNB to find out what was the problem and asked if they could reverse the transaction. The person on the other side was so reluctant to assist and I had to ask to speak to the Manager who also said I must liaise with the supermarket as there was nothing they could do. So as we speak, the transaction is still sitting on pending payments (i.e. from 5th Aug 2019 to date) on my bank statement and the supermarket could not release the goods s they had not received the funds. Now I have no clue who to contact in order to retrieve the +/-R2500.00 which no one seems to know how to reverse it. This is very troubling if your own bank treats you like this. I hope this will be read by someone responsible at my beloved FNB.