Iphone 5 from Hong Kong

Hello, I couldnt call internationally and I have a problem here. Like 3 weeks ago, after an architectural project, one of the architects gave me his phone(he is from hong kong, I am from USA, and I still live in USA). And now he turned back.

However now, on the screen Iphone 5 has some dead pixel(like these pixels are always dimmed). I contacted Apple Care here, they were about to change it, but then they said that it is impossible for them to change this Iphone because its from Hong Kong, some international issues.. So they advised me to contact Hong Kong Apple care. But I have no idea right now to do. What should I do right now

Thanks