Does she come to your house to drop off & pick up? If so i would invite her over for tea and show her the quilt on the frame. Easier to show than explain.
Having said that, I don't quilt for a business, but do quilts for friends and family. I've done several for someone who should know better, but has given me tops in the past with wavy borders. Somewhere on the board I read that quilting a piano key will take the fullness out. this worked for me. It's a bit of work because it's not a continuous design and you have to measure. I start in the center, and stitch the first 'key' down, matching centers of top and backing. Then the edges then half way between those quilting lines, each time measuring the centers of top area and backing. Basically you are doing an easing in process. I continue until the keys are about an inch apart. Another down side to this process is that I have to turn the quilt as you really can't do the sides this way (well, I can't anyway). Might not be the solution for this quilt, but it's a good technique to know.
Of course there's always the amazing quilters. Look at this video:
http://www.youtube.com/watch?v=lPHsBYa36W0