My iPhone 6 immediately went to no service or searching after the update to ios 9.3. Did a factory reset and reloaded 9.3 and that didn't help. Got a new SIM from AT&T and that didn't help. Went to the Apple store and they made me purchase a out of warranty replacement saying the update couldn't have caused this. I explained to them that it happened right after the update but the didn't care. Is there anything I can do now?