Attitude from staff

I'm very upset with the attitude I received from a cashier by the name of Nkosi Z Nkosi. I bought 2 cans of baked beans, 500g macaroni pasta, cheese twirls and niknaks. She rang 2x plastic bags. Instead of reversing the second plastic bag she folded it for me to take it home. I never asked for an extra bag. Is that how pick n pay operates now? Why she never asked for supervisor to void the plastic bag? I want my 80cents back as I never took the empty bag