FNB AGENT GIVEN BAD SERVICE

I called the banks loan department to have my debit order changed from the 23rd to the 25th of each month.It was clearly a mistake on their side from the beginning after speaking to this agent she refused to have it changed to the 25th and when I asked her to speak to a manager a few yes she refused.I asked her name and reference for this call she also refused.She then damanded that I get proof from my company to confirm that I get paid the 25th of each month ?