I was called a fool by a cashier

yesterday afternoon around 17:00 i went to SPAR too do some groceries. The cashier couldnt accept the R100 note i had as it was stained, i drove back home to get the money and went back. when i approached the cashier she started the stained conversation again of which i saidd to her, its funny how you dont check the money you are giving me but you check the money i am giving you. and she said and i quote \ you are a fool to have accepted the satined money and you came her thinking that you are going to fool me"this she said in front of the white lady who presented herself to me as a manager and a whole lot oof customers who were there too. and when i asked the lady \""manager\"" why her cashier is calling a fool she said the cashier is just doinng her job. so i am asking myself if the Spar casier job includes insulting customer"