Bad customer service

I went to usave Itsoseng to buy groceries and was not allowed in as I had no mask on even though my face was covered,I went back home to get a mask,as I was paying in store I noticed the guy behind me had no mask on ,I asked the cashier how come he was allowed to enter without a mask,he then refereed me to the manager ,the security guard in charge of the entrance laughed as if I was telling a joke,saying he was not aware that the guy had no mask on..I am very unhappy with the treatment I got at usave Itsoseng