Reverse my money

So I tried helping my brother with his utility bill in USA using my fnb card. The payment failed due to AVS mismatch and was declined, however the money went off my account. FNB cannot reverse the money even though I provided an email from the merchant stating that the payment is declined, therefore there's nothing to bank. FNB is adamant that the merchant has to bank the money before they can reverse it. According to them if the transaction is still pending there's nothing they can do. I initially used Capitec card and the money was reversed in pending status. Then I used FNB because I was thinking the issue was with the Capitec card. MXM.