I would not stop at phone calls and emails to UPS. Find out names of the higher ups, thier office address,etc and send them a registered or certified return receipt w/signature required. In your letter be very specific about what happened and what you expect them to do about it--all the while being very nice, not nasty-you catch more flys with honey than with vinegar!
Good luck and I hope you have your beautiful quilt back before you read this!