Total disrespect

On the 10/11 April 2019 i went to the Mr P Home in Canal Walk to return items I had received as gifts on my wedding. Cashier (bongeka) assisted me very patiently & she offered me the best service. I wanted to return duplicate goods over R2000. I did not have the receipts as the items were gifts. I explained to bongeka and she said I could exchange things of the same value. She then added the value of the goods on to a gift card. I used the gift card in store. As she was ringing up the goods our entire conversation was in venac. Her supervisor ( patiswa/pateka) demanded that bongeka speak English to me & I told the supervisor venac was find. As bongeka rang up the items the supervisor questioned the amount of goods that are being purchased & if the purchase was legit or not as if black ppl don't shop for over R2000. Bongeka explained that she was doing an exchange for me. She(supervisor) kept telling cashier to speak venac and cashier explained that the customer was speaking venac. The super visor threatened to fire the cashier and that she will get whats coming to her. So unprofessional of the supervisor to reprimand a worker in front of a customer. They both argued right in front of me & my sister who was accompanying me. I even intervened to stop the argument but the supervisor turned on me. I could not complain at the time as the was no manager besides her. I was so disrespected and intimidated as she stood over the cashier the entire time to check what was happening. Her(supervisor )last words were "ill deal with u after that sale & I'm going to check if it's legit " all this was happening right in front of me. I even told the supervisor not to undermine me and she did not care on bit. The entire store was baffled at the supervisors behavior. I even left the store without completing my shopping as i had a few gift vouchers left that I wanted to use. I have never been disrespected by a store like that in my life.