Here is a story for you.

Caused me much indigestion.
I have a buddy, a Scotsman who lives in Germany, who went on a vacation in England. He found a wooden forearm with nosecap for sale of a type that I had been looking long and hard (about ten years). He snagged it and mailed it to me here in Canada as an antique wooden carving. I was so excited when it arrived at my back door by courier obviously opened by Customs.
The courier had customs documents etc and an invoice, he needed $256 (cash or cheque)

before he would hand it over to me.
I refused delivery and we ticked "Return to customs for review" box and off it went back with him.
It disappeared into limbo and after a few weeks, no expected call from Canadian Border Services. Calls to Post Office and Can Customs came up blank. Customs said it was a Post Office issue, Post Office said it was CBS issue. Six weeks later after calling CBS once a week, nothing. It had just disappeared. Sadly, I had no tracking number for the return to Customs. Nobody could help me, or were interested.
So I talked to my Post Mistress at my small local post office and she went to an old school hand written log book that was kept up to date by her letter carriers. They write in the log and peel a bar code sticker off return packages and stick it in there. She found a ref number and went on line, poked around for a while. She found that it had been tagged 'undeliverable' and 'return to sender'. Problem was the sender had now finished his vacation, was long gone and was back in Germany, the package was on its way, somewhere between Canada and England (again, no tracking).
Oh ya, forgot to tell you. This was a forearm for a rare 1896 Martini Enfield Mk.I cavalry carbine, nice shape with minty nosecap. Not easy to find one, never mind another. So close (my back door step) yet so far. I would lie awake at night pissed off.
Then one morning, I got an email, it had showed up back in Old Blighty. Buddy did a quick trip before Christmas, recovered the package, sent it on to my father in northern England who repackaged it and sent it on to me with Christmas stickers on it and marked it as a 'gift'.
The thing was back at my back door again last week, unopened, no duty or takes payable. Woohooo!
I love a happy ending