Hello. My iPhone 4 lock button has become stuck. I'm believe it's because of a defect. I'm still under my 1-year warranty and I plan to go to the Apple Store later today to exchange it. However, I have two quick questions. 1) Do they replaace your phone with a new one or a refurbished one? 2) Can I exchange my black iphone for a white iphone? Thanks in advance for your replies.