Send it to your uncle. He can take it an Apple store in Miami (there are 5 in and around Miami) and get an immediate replacement.
Apple Store The Falls8888 SW 136th StreetMiami, FL 33176View store details
Apple Store Dadeland7509 North Kendall DriveMiami, FL 33156View store details
Apple Store Lincoln Road738 Lincoln RoadMiami Beach, FL 33139View store details
Apple Store Aventura19501 Biscayne BoulevardAventura, FL 33180View store details
Apple Store The Galleria2388 E. Sunrise BoulevardFort Lauderdale, FL 33304View store details
I believe you will have to send the iPhone to Apple from the US address, not from Chile. To send the iPhone to Apple from the US you can use this link for assistance: https://expresslane.apple.com/ServiceOptionAction.action
Thanks, but if possible I'd prefer to send it directly to apple
Apple will not accept shipments from outside the country and they certainly will not ship it outside the country to return it.
If you do not want to bother your uncle, get on a plane and fly to the US, get it replaced and then fly back home.