Pathetic service N1city McDonald's

I went to McDonald's N1city this evening and got the most pathetic service ever. We were given cool drinks which was flat. I went to the counter and politely asked if i could please exchange. A lady by the name of Irene (wearing specs and had a tattoo on her arm) completely embarrassed me in front of everyone. She shouted and said that all the coodrinks were flat and i could only have apple juice, she was even getting annoyed when i asked if all the cool drinks were flat. I agreed and took the apple juice and not once did i get upset with her or show that i was getting annoyed . The manner in which she addressed the situation was completely unprofessional and very disrespectful. Why serve cool drinks if they are flat anyway??. McDonald's is of my favorite fast food restaurants however, I will no longer be going to McDonald's N1 city because of this pathetic behavior. Please address this issue ASAP.