I'm so sorry this happened to you.
As a longarm quilter for others, I would have immediately offered to have you mail the quilt back to me AT MY EXPENSE using the quickest way possible. Humans are humans and make mistakes...but they need to be corrected quickly.
How about the Press N Seal product? I think that would be great. I like the idea of making a copy of the block on a copy machine, too, but think Press N Seal is the way to go as it will adhere firmly all over.
Before you do it on the quilt, practice on several quilt sandwiches to make sure the stitch length is close. This pattern and the stitch length might be difficult to duplicate exactly, but depending on the length of stitches your machine can stitch, you may be able to pull it off.
Good luck - please let us know how it turns out.
Nan --Indiana