So I'm fed up with my slow wifi on my new 3GS. I've had several friends test theirs and they get close to their home circuit speeds over wifi. I get 600 Kbps on a 3.0 Mbps line. So I've decided to take it back to the Apple store and have it swapped out. Will they wipe my old phone right there so I don't have to worry about any of my data being compromised?