Contact the shipper, USPS, DHL, FEDEX, UPS and open up an investigation. I know USPS has an investigation team that deep dives this stuff in coordination with the FBI due to the criminal elements being involved.
Ebay selling my missing amplifier
8 months ago I sent an amplifier to europe for upgrades. The amp went missing and there were investigations that went unresolved. I happened to be searching on ebay and noticed the amp and when I magnified it Bingo the serial number was same. It is an ebay seller store that is listing it. Ebay has not yet responded after several attempts. What next?