have a p900 and i'm very satisfied..
in 1 month its out of waranty and i have discovered yesterday that the button for power on,off (in the side) doesnt work and it can be pressed much deeper than before..
so if i go to the service shop the will tell me that its not in the waanty because its my fault..
is there something to do in the phone so they cant refuse to trade it whith a new one?
i have only one month till the waranty is over so everything is more than helpfull
thanks..

If I were you, I'd just send it directly to SE. They are pretty generous most of the times. Just send the phone with a note what is wrong with it and that it should still be under warrenty, and you'll probably have your (working) phone back in about 3 weeks... (unless offcourse it really IS your own fault, but you can always try this, I had some good experiences with it myself)