Unable to elect the original debit order dates for FNB Home Loans

I recently took out home loans with FNB. Unfortunately the debit order dates that I elected were not upheld by FNB and were ignored when setting up the account. Now that I try to change it on the app, it doesn't allow me to change it. Every time I try my request gets ignored. I have tried it via email as well but the fnb staff only respond after two weeks every time and don't meet the cut off date for the debit order change. As a result, they cancelled the debit order for the one property without giving me any notice of this and I received an SMS from FNB stating that the bond was not paid. I thought it would be going off on the date elected - since no one said anything to me about cancelling it. Result is that it looks bad on my credit history, at no fault of my own. And it is still not resolved many months later. This level of incompetence is unacceptable and very disappointing. I gave FNB another chance with my property company but now I regret it because just a simple task like home loan debit order date change is proving to be impossible. They either don't want to cooperate and are doing this intentionally. OR They are just that incompetant that no matter what I try, phone calls (unanswered for long periods of time and cut off after answering), emails (unanswered for weeks and when answered the answer is cryptic, in poor english and no resolution is found), app (technical issues such as no self service tab, no result after setting the debit order date, etc.). I am at a loss of what to do to get this resolved. I am hoping that posting here will finally help me get my debit orders set up the way I elected them to be upon approval of my home loans.