Yea, I'd try to cancel the extra line assuming that it's just an added line to your original plan for now. They will require a utility bill...they aren't idiots.
We're going to dump our Sprint, and they decrease their early termination fees every month that you have the contract, so when it gets within reason (I think the last 6 mos it's only $50) they are gonna be gone. You might look into prepaid or something w/o a contract if you do get into something else if you manage to get out of this.
If you call them and just talk to them about your situation, they will normally try to work with you somehow. If it's not about service, and it's just about price...they can find a promotion or something to help you out.