FNB Debit card disputes

Good day FNB , <br> I I was traveling abroad in America Florida , I by accident used my FNB debit card and not my FNB credit card (R3000) , my transaction was declined by the merchant and also I received a sms stating transaction was declined, (did not kept the declined slip at the time did not know I will need it) the following day I received a sms stating the payment went off my debit card. After numerous calls to the FNB customer call centre to resolve this , now I received an email for debit card disputes that I must now get a letter from the merchant ( IN AMERICA ) that the transaction was declined , surly you are my bank and I relay on you to handle issues like this , I don't know who or were to start phoning now international to have this resolve. Please help to resolve this.