thanks for the advice. mentioning shabbos didn't get me very far because it was already sunday evening. but after a few very long holds and unhelpful reps, I negotiated with the supervisor (the second supervisor I spoke with) and offered to pay $100 instead of $250. (I explained that I'm a broke teacher :-))
he agreed. he said that they can't just waive fees - they have to show a charge of some sort when they make a change. so I paid $100.
it was very time consuming, but i'm happy I saved the $150.
hope this info helps someone in the future...