The issue is that while restoring from a backup the problem will follow you .... you have to do is restore as new iphone .... but if you lose everything, obviously if you keep it.
On the other hand if you do not have the original sim .... because if you go up to 4.0.2 if you have original sim will stay locked.
The truth that you are in a bind .... but hey would tell you that if you need a rush .... do not do the trip ... and when you have time you do it quietly.
Things hurry, but in this, never go wrong.
Regards, osky