OK, you had three kids in teh car, it was pouring. Makes for a stressful situation. I understand the frustration, but it sounds like you let your attitude get the better of you. If what you wanted most was to get the meal the way you ordered it, you should have hung in there a bit longer before raising your voice, acting irritated and becoming testy.

They were gernerally trying to serve you, their customer. Yes, they made some mistakes. And it sounds like you yelled at them because of it. After that, it is all downhill. If you get to have her fired, she should have the opportunity to get you fired from being a customer at any fast food joint.