Verrrryyy bad service and bad attitude from a cashier

I was helped by a very rude cashier by the name of Sonto Khanye at Shoprite sontonga mall, the customer before me paid cash nd i saw her counting R500 right in front of me after scanning what i was buyung i asked forR400 cash back she rudely ans**** me and said she doesn't have it she only has R200, i even asked her is she not allowed to give me the one i just saw her counting he said she reserved for someone. I then waited on the side luckily the lady behind me was paying cash asked for R200 from the cashier, i dont know which button she kept on pressing as my transaction said declined when i asked yo see the reason for decline as i know the card has money and my pin was correct she told me to come and see for my self on the screen. I then asked for aslip to see it was writted VOID TENDER PURCHASE. im really angry at the service i got at Shoprite sontonga worse being made a fool of and told my withdrawal os declining