I guess printing out the regulations to show them wrong would be futile and cause them embarrassment therefore making them dig their heels in even deeper. Might try writing your displeasure to your local Congressman about your PO refusing to provide you legal service. Sometimes a letter of inquiry from their office to the local Postmaster will get you their cooperation. From what I understand written letters get more personal attention and a possible response then being overlooked in the overwhelming flood of easier sent emails, only cost you a stamp to see. Keep us posted
YMMV