3G data on my iPhone 3gs isn't working?

I have 3G turned on, and for the past several days it hasn't been working consistently, it won't always connect and it'll tell me there's no current connection. It works perfectly fine on Wi-Fi though. Is there any way I can fix the connectivity with the 3G?

Added (1). I did a network reset yesterday, and I'm still having issues

IPhone 4 vs Nokia Lumia 520?

Right, for Christmas i can either get a Nokia Lumia 520 or my sisters iPhone 4, its a couple of years old, just wondering which would be better all around?

Does Apple Carry Unlocked iPhone 5s's?

So I'm on apple's website and am confused as to wether Apple sells unlocked iPhone 5s's in the US? Because the only unlocked ones are for T-Mobile? Are unlocked ones available in store or something?

My iphone 5s button feels loose and I don't have a warranty?

I got my iphone 5s on October 10. I don't have a warranty or insurance on it. My home button feels wiggly and loose; it makes little clicking sounds. Is there anything i can do? Will they replace it because I have never dropped it or anything?