Poor Service from FNB

I am a client for FNB for many years and have been happy but recently they are acting so unprofessional. I bought a property using their home loan and when I sold the property there was a shortfall and they never initiated a debit order process for the repayment of the loan for over a year they never contacted me in regards to it until they handed me over to collections and after that I have been calling and following up on them to debit the amount from my account after completing the debit order form even this month the money was supposed to go off on the 25th of October they have not debited and this is affecting my credit profile and am trying to buy another property and I have enough money on my account to pay off the shortfall. I even asked them for a EFT account so I can process the payment they never responded with the detailed am so disappointed with their poor service.