Sorry I don't have a solution... but as a longarmer, I usually ASK the customer if they want the excess trimmed 1/2" to the edge, leaving 1/2" backing and batting/wadding sticking out beyond the top. I don't charge for this. BUT... it is NOT the same thing as "squaring up".
I'm so sorry that you have this situation. It would be a good idea to show her your top and explain the problem. If that had been my goof, I would have apologized profusely, learned from my mistake, and offer either a discount on the existing quilt or a discount on a future quilt. If she truly wants to be a professional, she will appreciate the insight.
