When facing a customs clearance event, firstly check where the package is blocked - on the departure or arrival country - to identify who should be contacted for follow-up.
Meanwhile, it is mandatory to gather at least the following information: packing list and the commercial invoice or proforma invoice.
If either the sender or the receiver work with a customs broker, also enclose the agency’s information to the other documents.
Customs are not handled the same way in every country, so the next step is to contact the local parcel courier and receive instructions.