I have run a postal box/shipping business for 26 years. I try to never send a valuable package thru USPS. No one is held accountable when there is a problem. Please send quilts by UPS or Fed-X ground. You can pay and print labels from their websites and avoid the mark-up price at a store. Also the benefit of tracking # and exact date of delivery.
For this lost package, go online to complain. They will start an inquiry from above. The local postmaster may not officially record your complaint because he can only have a certain number on file. So very sorry for the 'lost' package.