There is a system for congressional complaints that makes people act.
Do you have any idea how many calls a day a supervisor answering the phone receives? Not just "where's my parcel" but the patron has data that states intermediary carriers (ups to PO for last mile)
Thousands of calls a day. With 31,606 offices there has to be at least 2-3 calls per day.
Search harder is a congressional command. (Besides all their political mail is free to them)