There are three lines on my contract I have one of the phones and my two cousins have one. As of right now the phones are off because they wont pay the bill so I decided I'll cancel one and give the other one to someone who is going to pay the bill. December bill was due on the 20th, and they have already billed me for this months (January) bill. So when I cancel the contract will I also have to pay the their bill?