I would take EVERYTHING away. Leave her 4 pairs of cloths and a notebook, sketch pad and a pencil. MAYBE a book, and colored pencils. I'm talking it'd be at least 3-4 weeks before she could earn things back. Sure if she goes to her mom's you'll hear how horrible you're treating her but don't budge. I don't know if you've gone Christmas shopping for her yet but keep it to books, and cloths maybe if you did get her stuff she can earn that stuff first. She's going to rebel hard and this sounds mean to do but you need an attitude change fast even if it's just at your house. I would take everything out of her room while she's at her mom's that's so she doesn't throw a huge tantrum while your removing her stuff.