Wow, a lot of complaining and what? Not all your stuff yet?
I am going to interject my opinion, following a 41+ year career first 30 years in the US Military and the last 10+ years as a US Customs and Border Protection Officer.
Remember the old adage about catching things with honey and not vinegar? Remember please and thank you? In my almost 11 years working on the border between Canada and the US I have heard most of it, see more then I care to remember, and have watched someone turn beet red in the face, stammer, stutter, almost get spit on their chin, all the while I am becoming nicer, the smile bigger, and calmer. It really torqued the guy when I did that. But there is a point. He was a USC who was breaking the law by trying to bring $6,000 worth of Lladro Crystal into the US for Christmas Presents. By legal rights we could have seized all the items and told him to have a good day. Since it was Christmas we "helped" him and only charged him the 1% duty.
What was the issue? He walked into our facility demanding that we didn't know our jobs, that we were a joke, and couldn't do anything to him because he was a USC. He came very close to being arrested for attempted assault on a federal agent and even closer to a 2 second blast of pepper spray in his face - except we kept our side of it calm and cool!
I guess bajo_cero said it best - if it were me and I had "things" in boxes being held by Customs and I wanted them I would have probably walked in, politely told someone why I was there, and asked someone what exactly do I need to do to take custody of my property. JBHenson you start out talking about scientific equipment and later, toy cars in boxes; as a retired Customs Officer I would have been a bit more detailed in what it is you're bringing into my country if you were at my border.
I am not really conversant with the Customs Laws of Argentina; but in the US and Colombia, when entering the country the words "Do you have anything to declare" means certain things have to be declared when they come into the country. I do know that a customs declaration needs to be completed and unaccompanied goods also need to be declared - and commercial goods are prohibited. (from a google search: "what items must be declared when entering Argentina). I suspect those "scientific equipment may be considered as possibly prohibited.
Bottom line - I try to be very low key everywhere I go. If I am asked a question in Spanish that I don't understand, thank god my wife is with me; I am still in kindergarten when it comes to speaking Spanish; but I am a very good judge of people - the safety of me and my fellow officers depended on that skill.
One quick anecdote from my step-son, who is Colombian but works for Aerolineas. Because of the situation he now has a camera mounted in his car. He was stopped by the police while driving one day, seeing he was Colombian they started in with "ah Colombian, you are smuggling drugs". As he says things were getting intense, he was worried they were going to plant something in his car. He remained calm (he really is very laid back and is wise beyond his years) and said, but I work for the government too...showed his work ID and received apology upon apology. Had he became aggressive in his response, after they handcuffed and beat him they probably would have "found" drugs!
Be polite, we are guests, especially us temporary visitors for a couple of months, we need to learn the cards in the deck and how to play them. It goes a long way when you ask someone for help or advice instead of demanding something.
