Refusal to change December early debit order

I was sent an sms that debit orders will run earlier this December ,so seeing that I will be getting paid exactly month end I called and spoke to Anthonia to ask her to keep my debit orders on the last day of the month but she told me it was not going to be possible because they have already closed the cut of to change debit dates..how can the bank decides to change debit orders and when you advise them to change and you are told such?the only option she and her manager gave me was that it will be reversed at my expense..Iam so unhappy because Iam going to be charged for something that I wanted to avoid..