I know..I feel bad for you.
What a way to begin your vacation specially when it's well deserved!!
Chances are since you sound like you have good communication with her and she can come to you if she has $$ problems and know you will help that this was something she didn't know her self. It will prob. be embarrassing for her but you will have to stick to your guns and tell her that you need to be paid what you agreed on and the nsf fee. You can't pay for her mess ups that isn't fair.