I have had my iPhone for about 3 weeks now however recently it has started freezing on me. What happens is that when the screen is blank (eg not been used for a few minutes) I cannot get the phone to come out the blank screen, pressing the power or home button does nothing. I have to hold the power and home key together to restart my iPhone. This is really annoying as the phone will still ring if someone tries to call me but I cannot do anything as the screen is still blank and unresponsive. This has happened 4 times now in the past week, it doesn't happen all the time but it is still very frustrating. Should I return the phone to the O2 shop or take it to an Apple store? Will they give me a new iphone to replace this one?