Cashier bosses at PEP

I made a lay bye at PEP in Alberton City about a month ago, I went to pay the balance on Sunday and I also wanted to pay for other goods a well. When I go to the till, the cashier who's name is Phumzile. The cashier did not greet me, she told me that I can not pay for the lay bye and buy the other goods in one transaction and she already sounded irritated by this. I sighed about the two transactions but before I could say anything else she shouted "What should I do", so I calmly asked her why is shouting at me. She then carried on to shout at me and I asked to get my money back, she called Zama to "overide" and Zama was just as rude. This all happened in front of my children and husband. I felt so disrespected and I have been wondering the whole time what made them to think they have the right to talk to me like that.