They started a case for me, and eventually called back to tell me they spoke with with mail carrier who was the last to scan the package, who explained that the package was routed incorrectly, but they had it and would be delivering it shortly.
In another case I've also had good luck simply calling the sorting station and talking with the actual human who handled my package (there was just a backlog and it would be delivered soon).
I did not get an "corporate vibe" either time, but rather was able to communicate with the actual person who would know.
My mail got delivered wet a few times, so I complained. And all they said to me is, it got wet because it was raining. They basically said that there is nothing they can do when it is raining...
Don't put out any outgoing mail. Even if yours is dry it will get wet when it comes in contact with other mail that is wet.
If you can hold off sending a letter in the rain do so
If it's raining the wet letters get tossed into a bucket, then into a larger hamper than into a machine for sorting.
Wet letters make other dry letters wet. So even if you take them to the post office they may encounter wet letters in their way.
Ink runs.
Although I have had Canadians tell me that their postman does not pick up outgoing mail. Thats what I thought. DUH!2
And if you think the story is even a little bit better losing a package at UPS or Fedex you're delusional.
If you're kind, and exceedingly polite to them, and are as understanding as possible, they'll be incredibly helpful in return.
The people that deal with lost packages and lost mail are used to being yelled at, berated, and treated poorly, so they often react surprised and helpfully when you go out of your way to be as nice as possible.
Most importantly, the best advice I can provide is to have all of the information you can possibly provide written down first (preferably typed so they can read it easier), along with a detailed timeline, and copies of any supporting documentation.
Basically you'd call a number or send an email with your problem ("File claim for missing package," "Put me in touch with a human being at the USPS," "Cancel my Comcast service," that sort of thing.) The service's agents would then waste time navigating phone trees and dealing with red tape on your behalf.
Seems that there'd be a lot of potential customers who could use a personal assistant but can't afford a full-time employee. Obviously some tasks would require granting power of attorney or other scary legal maneuvers, but plenty of others wouldn't.
I offered a $500 bounty to anyone who could help me locate the package. It was worth that much for me to recover it.
In the end, both USPS employees that really helped me out the most turned down my offer to send them the bounty.
I realize there's a dark side to this suggestion: it weakly incentivizes loss for the purpose of getting a reward for it, and makes getting help a luxury for the wealthy.
However, the current system of only helping when cases hit the media doesn't work either. Obviously they can't afford to do exhaustive searches for every last piece of lost mail. There needs to be some sort of middle ground, where value and personal importance of the package is weighed against costs and available resources.
Probably the first thing that needs to happen is for the USPS to stop getting bled dry over pension payouts.