Well, firstly, none of the items in the package were on the Do Not Import List. So the store, FedEx nor me knew not to send the items. Aduana decided to open the package and call into question one of the items. At that point, the only thing that can be done is the purchaser must hire a broker and/or get papers for the item in question. It is my understanding (and I`ve had a 48-hour crash course in these matters) that neither a store nor FedEx has responsibility for obtaining proper papers. I am guessing at this point, that that is the purchaser`s responsibility. It`s a crap shoot when you order something from the States and have it delivered here. It might get stopped by Mex customs (Aduana) or it might not. One can avoid much difficulty by looking carefully at the Do Not Import List and not ordering anything on the list. But other things are left to chance - whether Aduana decides to hold something back from delivery or not. If they do, it seems it`s basically impossible to regain access to that item, indeed to the entire order as in my case.
In the future, I will be having things sent to a broker house in Texas like Sol y Luna and having them clear everything and send it on. The expense is only a little more than having something sent directly from the store in the US to my address, it turns out. And they can get things here faster as well.