Quilting for others is probably one of the most stressful things I do. But the satisfaction I get when I am finished makes it all worth while. When a customer says "do whatever", is my "whatever" acceptable to her? I have been quilting for hire for six years now and with every quilt, I do feel as if I improve. But to get to where I am now, it took quite a bit of time and practice.
Tension can make or break a quilt. It is obvious she had issues with her tension. I never would have been satisfied letting that out my door.
I am at a loss as to advise you what to do. Did you see her work before you became her customer? Did you discuss this before you paid her? If you did not she may have thought you were satisfied. This may be one of those times where you just take it out and have it redone by someone else and just not go back to her again.
Please let us know how you resolve this. Sorry I can't be more help.