I live in Chile and I need to send my iphone for repair to the US.
My uncle lives in Miami, so I used his adress as a shipping adress for my repaired phone. I dont know where to send it though.
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.
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.