What a nightmare... as a non-confrontational person, I applaud you for bringing it to her attention. And I would give her a chance to fix it. Is it possible for you to see other quilts she has done so you know how typical this is of her work? She may have rushed it and would do better next time - especially with this one since she knows you'll be checking.
As for washing before sewing on the binding, I have done this once and had no problem. I machine sewed it on before a long car trip to the house of the recipient. I had to wash it before leaving and then hand-sewed the binding in the car. It worked out fine.
Good luck and thanks for the work you do!