I realise everyone has prob heard all this before, and I'm sure there are thousands out there like me...but please, how can I deal with my totally OBNOXIOUS 13 year old daughter. She is so mouthy and rude and aggressive, to me especially I am at my wits end.her elder sister is 18 and her younger sister upsets her terribly with her obnoxious behaviour toward me and others. I just don't know where I've gone wrong. I can't understand how she treats me like I'm dirt, and speaks to me like that too as my other two girls didn't, in such a"in your face" aggressive manner.She has the biggest chip on her shoulder ever. I feel like she'll drive me to a heart attack at times she gets me so mad but nothing seems to work with her..taking her phone off her, not much use grounding her cos she doesn't care. she leads a nice life, goes to school clubs and plays an instrument (lessons and exams paid for by us), is going abroad with her band next year, ...but nothing we do is good enough