Letters From Germany

I'm wondering if anyone else has experienced the same problems as me: I have been sent several letters and small parcels from Germany- none of which arrived! They were all taken to the post office and sent from there, with the correct address and postage. In the meantime I have received dozens of items from the UK and the US without any problems. Any idea what could be going on??? It's very annoying, especially because some of those parcels came from my family and contained presents (which means they've not only lost the money spent on postage, but also whatever was spent on the content).