Not honoring contract

I have a personal loan and bond with FNB. I get paid on the 25th of each month and informed the bank of this when I submitted all my documentation. In the contact I signed, we agreed that my debit order will be on the 25th of each month.<br> <br> The last two months the debit order for the personal loan has gone off on the 23rd. I do not have the extra money lying around, so I had to make a plan to deal with my last two days before my salary would come in. I contacted the call center to correct the error today and I was informed that I have to bring a letter from my employer to the bank, to prove that I only get paid on the 25th. But my bond payment is debited on the 29th of each month, is this not the same bank?<br> <br> FNB was very happy to accept the proof I brought them to apply for the loan but they are now going against the contract. This means that if they debit me on a date that we did not agree upon, I will have a bad credit record. <br> <br> This is not Fit and Proper behavior, how can they change my debit date without my consent and then refuse to return it to the correct date?