Cross border private package delivery is surprisingly difficult. There are a few private companies. Our experience was that they fair but expensive. Our experience for Santiago-Lisboa last year with official Spanish mail was ok, but after it crossed the border and was put into Portuguese mail, they “lost” (stole) it. The tracking number (Spain and Portugal) trace showed it in Lisbon, but the mail staff just shrugged their shoulders. I spent a lot of phone cash trying to retrieve it but just got the runaround. I spoke to others that lost their BIKES that way. The Camino Portuguese and Francés were beautiful and we will do Norte next year. But many of our memories were lost by those thieves. My advice: use private and pay the money. Contact your hotel in Lisboa to see if they will keep it for you. Most do for a small fee, if any. Have the shipper deliver it direct to the hotel. Be SURE to get the EXACT Lisboa address and leave instructions for them to contact you when it arrives. Bom Caminho !!
DB&CB
Many times what happens when you send things across the border with the post office is the following.
You ship it from France or Portugal with the post office there. Once it reaches Spain most of the time (depending on the shipping product you bought I think) it does not get taken over by the Spanish post office, but by a private shipper in Spain that has a deal with the French/Portuguese post office. This is why the Spanish post office will not be able to help in many cases, since they never had anything to do with the shipment.
From my experience, if a parcel did have a problem (incorrect or not complete) address. It will not be sent to Spain (from France or Portugal), but sent to a storage facility in that country (could be Lisbon). They did not steal it, they just don't know what to do with it.
How can you get it back? By going to the company where you shipped it from (Portuguese or French post office). Yes, back to a Portuguese or French post office. This can be a pain if you are in Santiago. Calling might do it, but their customer service is close to zero on the phone.
Solution: Send it with a private shipper. From Portugal I like to recommend people go to "Mailboxes ETC" office. They ship with many private shippers like DHL, FedEx, UPS,... since it goes with the same company from start to finish, customer service is better.
That said, I do receive a lot of shipments from the Portuguese and the French post office every year. I would say 95% of the shipments go just fine... it is just a pain when you are in that 5% group.
Conclusion: Noone is stealing. Shipping is complicated... especially across borders.