Cashier with a bad attitude

<p>Today I went to PEP Three Rivers (at Shoprite centre). I bought rain boots for my daughter. After I left the store, I saw that I had two of the same boots (not left and right one). I returned to the store. A lady approached me and I asked if I could exchange. She asked me who the cashier was. I said "that one", indicating the lady behind the till, while I was busy searching for the slip in my purse. The cashier left the till, not helping the other client, walked to me and said in a rude tone: "It's not that one, it is Kate. My name is Kate". I said "how am I suppose to know?" She told me to look at my slip. I informed her that I am still searching for my slip... This is ridiculous! Like I need to know her name? Never in my life I had such a rude expierence at any shop. </p>