CY590329136DE arrived in Hangzhou customs on Nov 20. It is still waiting for import customs clearance. There might be two possible reasons for the delay:
1)you forgot to write receiver's mobile phone number in the parcel. China Post needs to send a customs clearance code to receiver which allows him/her to make customs clearance online. If this is the case, the receiver needs to call Hangzhou customs agent 0571-86896573/86896576. They will guide him to make customs clearance in person.

2)The receiver doesn't not want to accept the parcel and make customs clearance. This often happens when the parcel is a return for a refund. Many bad sellers often play such game to avoid refund. If this is your case, China Post can't do anything for you. You need open dispute to your marketplace like Amazon,Aliexpress etc, or call your bank to file charge back against fraud.

CY590329136DE was returned to Germany on Mar 7. Return parcels are very likely to be shipped by ocean vessel to Germany. So you might need to wait about 2 to 5 months to get the return parcel.