I feel sorry for you. It is tough to win when dealing with customer satisfaction long distance. And the longer the problem lingers, the more of a negative effect it has on you. If this happened to me, I think I would offer the customer her money back, take whatever you have learned from the incident, and be done with it.
Also, wanted to let you know that the pattern you chose, although very difficult with those curved points, makes a very nice looking design!