I need advice please. My teenage DD who is 14 was doing really well in first 2 years of secondary school then suddenly over past year she has taken a nose dive. I blame her socialising too much and social media like Facebook/BBm etc as she is always on these. We sat down and had a good talk about it all and when she went back after summer she agreed that she appreciates this is an important time in schooling and will knuckle down and study more. We then got a letter home for her being detained at school due to failure to do homework. So we grounded her as punishment. We talked about it again and she was sorry and promised never to lie about not having homework and to hand it in on time etc etc. Now even after all of these promises i have had another letter home, same subject, same thing not handing in homework.
I need advice, as my last punishment never worked what would you do?