In northern Argentina you'll want to check out Ecovilla Gaia, about 1.5 hours west of the capital, Buenos Aires. They have a website, several of the people there speak English, they do
PDC's and other workshops regularly, they have room for interns.
If you're willing to go to Patagonia, at the 42nd parallel in El Bolson is CIDEP, another permaculture community that offers
PDC's, and many other farms in that area.
Jerry