I'm really concerned for her (as I know you must be).
You punished her by taking away privileges, but it's not only made no difference, it sounds like it's made things worse. This tells me that as punishment, it didn't work. It has backfired. Which tells me - maybe punishment was not what was needed. At her age and ability, loss of privileges is perhaps a bit too infantile a punishment for her, anyway. I mean, if you are rude to your flatmate do THEY take away your privileges? No, if you are rude to a friend or a flatmate the consequences will be an increasing reluctance to do any favours for you, as well as perhaps a showdown where the friend or flatmate says, "Come on, man - what gives?"
I know she's not exactly fitting the description, but this is yet another case for "The Explosive Child". She's not typical, though. This isn't a kid with a disorder who can't help her behaviour. This is a kid who for some reason suddenly isn't coping, and who wants her parents to magically read her mind, and somehow make the problems evaporate.
There is something very, very wrong. I think she needed you to understand, and instead you punished her. To her mind, her last hope just evaporated.
From your point of view - I am not being critical of your parenting. You did what you felt was the right thing to do, under the circumstances. You had no way of realising it was going to backfire like this. I'm coming along after the event, with my take on things, because I have that luxury. You didn't. You just did what seemed to be right.
I would quietly talk to a teacher that you can trust to keep it confidential. Has the teacher noticed a change recently? Has the teacher noticed anything else that, taken with your own observations, could now point to some clues? A boy? A group of friends? Some academic, social or emotional challenges recently which may seem all too much?
Before all this happened, would you have described her as the sort of girl who would come to you for help? Or was she likely to hold it all inside and try to manage for herself? From what you say already, she sounds like this second type.
She needs to talk. I think you need to back off on the punishments. Don't worry about losing face by admitting you read it wrong - she's too smart for that, anyway. You would earn more points with her if you said, "We read it wrong. We need to talk about things and for now, we are dropping the loss of privileges because we think this is something way beyond that. You and we need to respect one another, and that means we talk to one another and listen to one another. It also means we must be polite to one another. We ALL need to work at this. We also care about you and love you, we don't like to see you hurting like this. If you can't talk to us about it, please find someone you CAN talk to. Nobody should have to deal with problems on their own."
What would happen if you tried this? At her age and capability, I think you need to move beyond merely parent-child relationship and start moving towards a more adult-adult one. This requires, as I said, mutual respect. But you are the parents, you need to set the example and show her (in how you speak to her and react to her) what you mean by respect. If she disrespects you, do not in turn show disrespect. Simply continue to be polite, but draw her attention to it. "I did not disrespect you; please do not disrespect me." It's Basket B stuff (read "Explosive Child" to know exactly hat I mean - there is a good summary in Early Childhood forum).
I know it sounds counter-intuitive, but it can work when at this age little else will.
I've used the analogy before - at a certain stage in a teen's development, you need to change your mind-set from "this is my child" to "this is my tenant." If you had a relative staying with you, certain house rules would apply and there would be certain standards of behaviour expected. But in return, you would also modify your own behaviour to the person staying.
I first noticed this when one of the teen kids had a friend stay over. I found my attitude to the guest was different than my attitude to my own child, who was the same age. It made me remember the years of shared student accommodation when I was at uni. I moderated my response to my own kids and found immediate improvement. I then began insisting (in the same respectful vein) that student house rules would apply. These were the practical rules of
* tell us when you will be in/out so we can cater for meals;
* tell us where you will be in case we need to contact you;
* put your dirty laundry in the relevant place so it can be washed for you next time we do the washing;
* don't bring people home without first checking with whoever is catering that night;
* share the tasks equally with other house mates;
* if you're going to the shops, check with other house mates in case you can pick up something for them.
These rules apply to kids and parents, equally. That way the kids can't whinge that you're only doing it to check up on them. The kids know that if I am going out, I will tell THEM where I am going and when I expect to be back. That way, they are more likely to do the same for me. I can't expect from them, what I am not prepared to do in return.
Clearly you modify these according to the age of the person (for example, imposing a curfew - which again is a matter of respect for other house mates; you don't come in at 2 am and wake everybody up. Instead, you do the right thing by your own current life and get home in time to get enough sleep to function at school next day).
All I've mentioned here is very superficial to what is really going on here. But it could be a start, to make it easier to find out what the problem is and hopefully begin to deal with it. I am really concerned that something has happened to really upset her, and she doesn't know how to deal with it or even how to ask for help. And as to what it could be - the sort of problem that could upset a very bright, very capable girl of her age - it wouldn't be something trivial.
Marg