iPhone supposedly synced to another library

I'm trying to help my wife get her iTunes unscrewed tonight but Apple support has been completely unhelpful. iTunes is saying her iPhone has been plugged in and is associated with another library which it is not. It has never been plugged into another computer aside from the one she used to set it up, which she's using at the moment. She obviously doesn't want to delete everything on it, which appears to be the only option. In the hour-plus long session with support, they told us countless times that the problem is that it was plugged into another computer, which I can guarantee it hasn't been. Then, as I explain this for the 15th time on this phone call, the guy hangs up on me like its my fault he's wrong and doesn't comprehend what's happening. Has anyone seen a) this issue with the phone and iTunes; and b) this level of pathetic support? I'm beside myself right now I'm so ****** off at them.