We had a girl we hired for seasonal help a couple of Christmas's ago. I liked her well enough. She was a bit...perky and a wee bit more gregarious than most people could handle, but she was eager to please and make things correctly. Didn't seem to be that much of a problem.
One very busy night (remember this is before Christmas) we had a non-stop line out the door. A customer walked up and handed this girl a bag of whole bean coffee to grind, specifying their filter and whatnot. They announce that they will be back in a moment to pick it up. So, my girl in question stopped what she was doing to grind the coffee. When the customer came back, they announced that they had changed their mind and for her to just throw it away. (We can't sell coffee once it's been ground.)
She watched in horror as the customer walked away and announced loudly so the entire store heard her, "I wish they had ordered a drink so I could spit in it."
Dear lord. I heard about her from every regular I had for months afterwards. Had many tell me that they would not be coming in as long as she worked there. (STILL couldn't get rid of her due to the upper echelon of management and their inability to actually manage.)
Fortunately, she stopped showing up for work so she ceased to be my problem. But I could so see a story about that happening here.
*As an aside, if you feel your issue isn't being addressed by one level of management, for the love of god, go higher. Sometimes the peon management is just as tied as you are and is unable to change what needs to be changed. If my regulars had gone to the upper echelon of management and complained loud and long, she would have been gone a lot sooner.