Bad Service

I have been coming to buy since Monday and the service has been exceptional from the Cashiers to the Packaging area to the Security at the Gate. Today has been the worst so I went to buy 100 Bricks and went to the middle aged with black short hair to pay. She look frustrated when I approached her then started asking the next Cashier for assisting as some of the items I took where not scanning and needed to manually typed it. After 15-20minutes standing next to her with an annoyed voice she says "sign here" and I responded excuse me with no please since I have been here for long waiting for you to figure everything and she gives a bad attitude and bad service. She shouted at me saying she is not from this department.