Sonic Drive-In

I took my little girl to sonic one day for lunch as a treat.I ordered her a white milk that they offer with the kids menu.It is in a small plastic container that is sealed.We took our lunch home to eat and when I opened the milk I discovered it had gone sour.I checked the date and sure enough it had expired,more than 2 weeks beforehand.I immediately called sonic to let them know about the situation and that they should check their supply to see if any of the other milks had spoiled.I was put on hold for several minutes and a was finally connected to a manager who harangued me about it being there busy time and could I call back.I said no,explained the situation and was greeted with a "well what would like me to do about it?" when I told him I had just wanted to make them aware of the situation he asked me to bring in the bottle to prove that I wasnt lying.I told him I would just call corporate and that is when he hung up on me.