Thanks everyone.
This is soo hard. As I said last night, my neice had a police caution when she took my sister's switch card. It didn't seem to have any impact on her at the time (my mum was at the police station with her as the 'responsible adult', because neither of her parents felt they could do it without blowing up), and obviously hasn't since, as she has done this. I'm surprised that the supermarket haven't reported this to the police, but it seems they haven't.
As someone has said, the problem with her having no job / no money is that she is likely to steal again. It isn't possible to keep a 17 year old in, is it? My sis stopped giving her lifts a few months ago (they live in a rural area). She just went missing one evening walked back home on her own at 2 a.m.
My sister and bil have confiscated 3 mobile phones from her over the years, because she used to steal to buy top-up cards for the phone. As soon as she got paid each month, she would just go and buy another phone, and the cycle started again.
My sister was having neices wages paid into her own account, then letting neice have a set amount each week (partly because she was supposed to be paying back what she took on the switch card), otherwise she would spend all her wages on the first day.
Now sis and bil will have to start locking their money up again, as neice thinks nothing of filching from handbag or wallet if it's left in the house. This isn't a good way for a family to live.
Believe me, this girl has been to several councellors over the last 3 or 4 years. No-one can get to the bottom of her, she has no regard for herself, and no regard for anyone else's feelings. She adores my mum (her Gran), but has taken £30 from her handbag before now, and jewellery from her jewellery box, which was discovered before neice had actually left the house, fortunately.
She has had love and care, and she has had discipline. There has been a time when she reported bil to the police for assault, because he told her off and locked her in her room for stealing from his mum. As bil works in a charity for young people with learning disabilities, he is terrified that she may have him charged for abuse some time, which would lose him his job.
My sister is now convinced that her daughter will end up in custody. Also that she'll end up pg, as she just doesn't ever think thru the consequences of her actions.
Sorry just sounding off, before I ring sis to try to express some form of sympathy.