My money

I went into a Shoprite and did 1 transaction, however my card deducted to amounts and cashier said on their side it had declined. When I got home I then realised that the amount was out of my account then I called my bank. I was told the amount is still in my account as it's pending however, I would have to fill in a debit order reversal form in order for FNB to reverse the money. Now I'm stuck here having to wait for FNB and their turn around times. I mean it's FNB and the merchant that made the mistake now I as the consumer need to suffer. Someone please sort this out. I am not going to wait for 5 working days for a mistake not on my side. How does one trust FNB as their bank if they cannot stand up for you? Kindly assist.