She thought it was "funny"? Hmm...something's definitely fishy here. I agree with everyone else on the letters - could you include pictures as well?
I never bought an MK bag before, but if I were you, I would write to a CEO and let them know you are returning the handbag and are very displeased! It shouldn't come to that, where you have to put something in writing but that is very unfortunate! An SA that behaves that way should be fired on the spot. Rule of thumb, customer is always right with some exceptions. However, a bag that is 24 hours old and gets destroyed is unacceptable!