Agree with Marc.
Often had the same problem with this as you.
The tracking is weak at USPS , UPS and also sometime with DHL.
Some parts arrived me where the tracking said it would be still somewhere in the USA.LOL.
Also the nice lying around on the german customs.
They real like to open my things, close my things send it to the next , open my things close my things send to the next...
3 weeks is nothing in wait till they get up there asses to send it along from Frankfurt to the next customs office, where i than have to wait till this guys write me a letter,
which takes also sometimes 2 weeks, that i should take my parcel there.
German thoroughness sometimes realy sucks.