Caltex Kiosk employee refused to sell items to customers

I have encountered a very poor experience of customer service at the Caltex garage in Armitage Rd, Town Hill, Pietermaritzburg, KwaZulu Natal. I was refused to purchase by an employee at the kiosk due to voiding issues where I was given the wrong product of goods and was not allowed to rectify purchase. I was denied to purchase due to the incompetence of the staff and the color of my skin. I deeply feel disappointed by the level of customer service and how an employee of such a franchise can be able to treat the customers in this way.