hmmm, well I don't know if you already do this, but I typically e-mail the rough sketch to the client before I begin the shading process (havent done that for the Buffy fund special because I wanted to get the drawings done ASAP) so they can request any modifications to the shape or orientation of the drawing before I put all that hard work into it.
I learned that the hard way when I completed a big 16 x 20, only to find out the owner had sent me the full body shot she wanted, but the wrong head shot and didn't want what I drew. It was frustrating, but she eventually sent me the head shot she wanted and I wound up redoing the entire drawing. It was my bad in a sense that I just "assumed" that was the head shot she wanted (which was essentially a blurred pic of the horse running in his pasture, so very hard to see the details) and didn't bother to confirm that via rough sketch. So, not sure if you did that with this client, but she may have been able to tell you to make the neck more narrow if she had seen a rough sketch first. She sounds very picky anyway and I wouldn't doubt if she saw a rough sketch, approved it, and then decided it wasn't what she wanted afterall...lol.