If you truly don't mind losing here, her money..... and quite possibly your reputation, I'd ask her for a meeting..... IN person. Explain to her that you've come to the conclusion, you cannot please or give her what she wants or needs. Here is a check for what was given to me thus far and say thank you and walk away.
Did that about 3 months ago. The guy came in balked at the price of the business cards (my cheapest cards), then balked at the price of the design fee, due to the fact that he wanted me to redesign Sistine Chapel. Finally, after an hour discussion of the redesign to his crappy card and I mean crappy card, the "I designed it myself" business card, he reluctantly gives me his 50% deposit.
So I design a really nice card, send the proof and received about 15 changes. I didn't like the guy from the gate and so I said SEE YA! Come back I will refund your money and you go have a party at another sign shop. Best 60 bucks I ever returned.
OH and one more, this happened today, I swear. This guy has come in before and ordered like a 25 dollar sign. You all know this guy, he is the guy that was in the business for 25 years and knows what it is all about. So he comes in this morning and wants two 8"x16", intricate cut, cut vinyl stickers. So we tell him 50 bucks, and I hear the "Oh well I have been in this business and I know what the material costs." My guy at the counter is like, "look dude you want two stickers intricate cut, we have to design, cut, weed, tape." And then he says he wants us to do it right then. We hesitate and say well I don't know if we can. So the guy who was "in the business" makes some snide comments and walks out the door, but not before my guy is able to call him a bleepin' idiot and to get the bleep out.
In conclusion, please know that we do not make it a habit of yelling obscenities at our potential customers, but sometimes ya just can't help it.