I'm a longarm quilter but I don't presume to speak for all longarmers. I can only speak for myself.
I've been in business for over 5 years. I give a work order with due date on it as your quilter did. I pride myself on professionalism, yet as we know, LIFE intrudes.
I've missed due dates on several quilts in the past 5 years:
Once I was injured and was on crutches, and unable to work for over a month.
Once my husband had emergency surgery and I was with him at the hospital and then helping him to recovery, and I was unable to work.
Once a part broke on my longarm quilting machine and I had to wait for the replacement part to be Fed Exd to me, and then I had to repair the machine.
On each occasion, I called the clients whose quilts were effected and explained the situation. All my clients were very understanding. I don't think they would have been quite so understanding had I not called them, explained my situation, apologized, and given them an estimate of when to expect their quilts.
I would suggest that you call your longarmer again. Explain that your quilt is a gift, and how important it is that you have your quilt finished THIS WEEK. Let her know exactly how you feel. She may not have understood that this particular quilt is for a gift and that you have time constraints. Let her know all of your concerns. I hope she will be willing and able to do your quilt next.
Good luck to you with this situation. Please let us know the outcome!