I purchased the iPhone 4 in February. And at first it was a great phone I really didn't find any problems with it. Just recently about a week or 2 ago the camera in the front its messed up. The screen is black with green and blue lines. And sometimes when I play a game or click on an app my screen goes black and goes back to the home screen. What should I do about this problem? Would I'd be able to receive a new iPhone, by the way I have at&t if that helps.