My package (postal) is being held at Zabrze, how can I get it released?

So I had my uncle send me a phone from USA through USPS which works with Poczta Polska I believe. I kept checking the tracking number and realised that the item goes through customs clearance twice each day. My uncle asked me to call Poczta Polska and they told me item is "zatrzymywany węzeł ekspedycyjno-rozdzielczy w zabrzu". The item is marked as a "gift" and they don't want to release the device. I keep calling them and no one picks up, at some point the phone is busy but no one ever picks my call. This is not normal but has anyone had problems like this and what can I do to get my item.

Woman at Poczta Polska told me maybe they need some "faktura" but how can a gift have that? Why don't they want to release my package?

Do they even know what's in the package? If yes, do they have the right to open it without my consent or presence?

They have the right to open and check parcels at customs
even if an item is marked as a gift it doesn't mean they believe it
many ebay sellers mark items as gifts to avoid import tax they will either accept a letter from your uncle stating the item was his personal property to give to you and he will have no finiancial gain from giving you this gift or they will get ***** and hold the item until you pay the tax or the item is stolen

Doubtful. If the uncle was sending his own phone to himself, he might get away with that but I've been asked in the past to pay tax on my own possessions.

They don't want to release it because the tax on it hasn't been paid. Given that there is no faktura, you can write them a letter stating what the value of the item is and asking them to calculate the tax you owe them based on that amount (hint: don't make the amount too low but obviously don't make it high either).

I had a pair of trainers sent from my cousin in oz and he put a letter inside stating the package was a gift and had a customs declaration from oz stating it was exempt from taxation luckily trainers are not seen as valuable items unlike phones computers or anything that sets off the metal detectors

did you pay tax on your own possessions because if so the receipt will entitle you to a refund of vat in the country you originally purchased them