Pathetic service.. utterly rude and unprofessional

Nice and hungry went to the ladies to refresh walked in Steers to buy food.. one my of sisters pick up that they don't have enough money however we placed one order paying separate. When informing Maxwell that we'll pay cash and swiping the difference he changed his face showed irritation, he threw me with my change and slip. Was stunned, when my sister asked him why is he doing that, she said you are wrong, he responded and said no I'm sorry I'm tired my sister, she then said to him but we are customers he said sorry. That's not acceptable I'm a loyal steers customer I've never seen such behaviour in my life. I'm disappointed and when I see steers I really get irritated thinking of the treatment I received. I don't want free food however please address the behavior as Maxwell is out of line. There's a difference when talking to customers and his g.. friends please reiterate