I would give her a chance to make good on the check... but keep a paper trail of all of your correspondences (and a written log of any phone conversations).
If you don't get satisfaction, let her know that you intend to take it further. If you write to the state attorney where her business is located and the state consumer protection agency, you'll most likely get a resolution.
I had good luck with a non-greek related business using the consumer protection agency. They sent in a mediator and got my money back.
There's a wonderful book that I bought and I higly recommed:
http://www.amazon.com/gp/product/037...lance&n=283155
It not only gives you fabulous resources (where to complain and to who) but gives you sample complaint letters.
Good luck!