Heidelberg mall gauteng cashiers throw fit over placing cereal or rusks in plastic bags

Its extremely rude each time we try to buy Ouma rusks at checkers in Heidelberg Mall Gauteng the cashiers throw a huge fit and make a scene whenever we ask them to please put the Ouma rusks and cereal in plastic bags too. They literally fight with each each time we ask for them to please put the Ouma Rusks and the Cereal in bags. Why do they throw a fit about this?! This have been happening for months. Extremely rude and disrespectful. WHY DOESNT CUSTOMERS HAVE THE RIGHT TO HAVE THEIR GROCERIES PLACED IN PLASTIC BAGS? Not everyone wants to carry grocery items one at a time up stairs!