Unprofessional services

I bought a new cell phone yesterday 01. 10.2019 at Pep store Eldorado Park at the cashier Nohlanhla and she informed me that if im not happy with the device i can return it in the original packaging which i did as didn't open the device as it the same device that i have which gives me problems. So on 02.10.2019 i went back to the store to refund the device and i was informed that i cant refund it and the cashier stand talking in Zulu which they thought i dont understood and i reply to them back in Zulu which was very unprofessional from them. Just because your store is based in a colourled community do not mean that we cant speak African languages which is very very common in our community as we part of the Rainbow nation and your cashier should think before they speak and they must treat customers with respect no matter the color of the person. They told me that i can't refund the unit so im dont want this device any longer and it has not been use and i still have the original invoice. I unhappy with the service i received from Pep store Eldorado Park and i would like to refund the unit and get my cash back.