I am probably going to be shot down in flames for this but for what it's worth here's my tuppence worth.
I do think the girl needs to make a substantiual contribution to paying the debt. But I do think this whoul d be split with the foster carer, after any negotiations with the telephone company.
Yes the girl ran up the bill. Was she really aware of the money she was using while doing so .......I doubt it. But she should be made to contribute to paying off the ££ as a learning experience, not a punishment. I really don't believe she ran up such a huge bill deliberately. What she did was typical teenage behaviour. My mum had to put a lock on our house telephone when I was a teenager as I could talk for hours with my friends, in spite of having spent all day with them at school.
The foster carer is also partly responsible for not ensuring a way of limiting the ££ used by the girl ( either PAYG or a limited teen tarriff) and as such should IMO help with the paying.
I think it's an important, and costly, learning experience for everyone involved. Not about bleame, but about learning and experience.
We need to teach children and young people to be aware of the financial cost of the things they use. But as responsible adults we too also need to take responsibility for limiting the possibility of young people running up such huge debts and ensure that measures are in place to protect us from then having to pay out vast sums of money unnnecessarily and which , with a little thought could have been avoided.
I hope the telephone company are understanding and reduce the amount owed somewhat and that this doesn't cause any undue friction between the girl and her carer. xx