IPhone 6 is useless at the moment. When you turn it on it will not locate a network. Phone is in constant searching for network mode.

Took it to the Apple store and was told that it is frozen due to traveling to different network zones and not transitioning to a new network. They say it is a rare occurrence that they are unable to fix. Apple did a network reset a complete phone reset along with software update. The phone is not under warranty so I was wondering if anyone here had any information that may fix this problem?