Complaint Review: United States Postal Service

My daughter mailed my set of keys from Detroit, Michigan to me in Huntington, Oregon. Only I received the bubble wrap envelope with the top slit open and nothing in it. That same day I showed the postmaster the empty package and filed a lost report which I have never heard a reply to, so, after a few weeks, I went into the post office and asked the post master to replace the post office key since they lost it. She informed me that if I wished another key then I must purchase it from her and that was that! This lady has had many complaints in her tenure here, and I would like to know why the postal service is never responsible for their actions?

Karen
Huntington, Oregon
U.S.A.