FNB failure to reverse debit order

FNB still has not communicated with me but only sent me a reference number. I don't understand how FNB allows new debit orders to go off on my account but they do not allow me to reverse it. I am utterly disappointed. It has been two weeks trying. In these trying times I am trying to make ends meet because a 6000 debit order that I did not authorize went off. I need this fixed. I will be looking at alternate banks because it seems FNB doesn't care that this is happening.