my gf once let one of her friends use her credit card to sign onto a cell phone plan.
you probably know where this is going, decided to ditch the phone after a few months and the guy was off radar for a while. she gets his phone bills so she just started calling repeat numbers in his bill. the guy was a cmplete douche, but eventually got the money to cancel the contract.
it's frustrating to see nice people willing to lend out their own money out of the goodness of their heart only to get screwed over by douchebags that don't have the consideration to take responsibility.
i wouldn't give up. call her from another phone number and get her to meet in person. it should be understandable to most people that a few hundred bucks is worth getting upset over.
Sleeping is a waste of time.