Bests & Worsts Reviews from Amazon

I bought a factory unlocked iphone 5 from this vendor while I was in the visiting friends in USA in December. When I opened the sim tray it stroke me that there was an ATT nano Sim there. Back home, I tried to activate the phone with my carrier from Argentina (Movistar) and the phone could not activate saying that my carrier's nanosim was imcompatible. So it seems like the iphone is actually locked (probably to ATT). We do not have oficial Apple Stores in my country so I'm stuck. Fortunatelly, I am travelling again to the USA in 15 days soI will book an appointment at San Francisco's Apple store to see if the can confirm that the iphone is locked and hoperfully they can swap it for an unlocked unit. I have paid more than 700 dolars and I can't use this phone. This is outrageous. AVOID!!!