We've had a lad staying with us since he was fifteen under very similar circumstances, he's now seventeen. Social services and the Police and bloody useless, his mother threw him out and he had nowhere to go, we contacted social services who did absolutely jack sh1t, and in the end we got fed up with trying to get either his dreadful mother or social services to see sense and he's stayed with us ever since.His mother still claimed his family allowance though and kept it for herself, greedy neurotic mare. I have no suggestions for you I'm afraid as we couldn't get any results from them either and short of packing him off and dumping him in their offices ( which we wouldn't do as we felt he'd been through quite enough) I honestly couldn't come up with anything else so he stayed. Good luck.