I recently used http://casillamiami.correos.cl to buy electronics from Amazon. You pay them for the forwarding to your address in Chile and also for the importation. Had them forward my Amazon purchase to my hotel in Santiago and package was there when I checked in. Worked pretty well. They seem to use Trans Express (http://www.transexpress.com/eng/index.php?lang=en) for the Miami to Chile part of the forwarding.
If you want your package to go all the way Futaleufu then your best bet would be Correo Argentino/Correos de Chile. The major bus lines delivering cargo within in Chile like Turbus and Pullman Bus have no service to Futaleufu.