I'm used to booking my award flights online and hate talking to customer service, but I can't input USH into the search. Is there any partner that takes you there on Star Alliance? I don't mind a couple stops. I'm just not sure if I need to call in or whether there are no award bookings available to patagonia.
you can book to EZE and purchase a separate ticket on your own to USH with aerolineas argentinas (AR) or when you arrive at EZE, you go to the other airport AEP and fly on a separate ticket with Jetsmart Argentina (WJ)
if you have some skyteam member's miles, you might want to book with them since aerolineas argentinas is a member.