I’ve never seen that happen in all my years of quilting. I don’t blame you for being upset. At his point, since it’s been washed, I think the only recourse is appliqué some cute shapes over the problem areas. Needle turn appliqué would be my technique of choice, since it isn’t adhered to the quilt underneath by fusibles, and wouldn’t show the lumps.
It’s not necessary to mention the quilt shop who carries this line of fabric, but I think it’s ok to share the mill that made this fabric so the rest of us know to avoid it like the plague. I would most certainly take the quilt in to show the quilt shop what happened so they can remove the fabric from their shelves.