Xenophobic staff

I was at the Shell by Wierda park/Amberfield last night at 20h11 to purchase a few items. I needed the price of Panados that were behind the counter, i asked the cashier, named Professor how much a packet cost in English and he ignored me. I then continued to ask him in IsiNdebele and his response was: "it doesn't matter what language you speak, i can't hear you behind that mask, you even sound like a " kwerekwere".. I went on to tell him that he can't use that term. He continued to ignore me again. I am a very bubbly person and interact with everyone that works at the gas station, i have been using it for the passed 7 years. Kindly address your Xenophobic staff, i had my kids waiting for me in the car and could not take the matter any further at the time.