With all due respect to Tom 1960, calling the USPS (local or 800) in my experience gets you lip service.
"we're doing our best", "we'll call you back"(rarely happens), "go to our website", etc., etc.
I'm waiting for a package "shipped" Mar. 25 which to add further insult does not have a tracking number.
The shipper says if it doesn't arrive by May 2, they'll send a replacement.