Does your daughter and her bf have the same mobile phone service where the calls are free to each other?

If yes, then I would demand that she stop the house calling or cut off the service to your daughters phone - as I had to do with my older son when his bill became my payment to make..... he was mad at first but calmed down after a few weeks and learned from his mistake of not taking care of his financial responsibilities.

BTW - older son is no longer on our Wireless Account.