maggie39 Hello from another 'worst mother in the world' prize recipient. I have a DS 14 and am familiar with the outbursts you describe, it is horrible but they don't really mean it. As mine says when I ask him about it later, he says 'It's just something I say when I'm angry'. Still it is very unsettling and stressful to live in conflict, I really hope they grow out of it...!
I think you are completely in the right by taking a stand. At the moment I am giving my DS the possibility of earning £2 pr day during the week, one for behaviour and one for doing a small job (such as emptying the dishwasher, sorting the recycling and putting the bins out, tidying his room, stripping his bedclothes etc.) This means he can earn £10 per week. If he doesn't do a job one day, he just gets one pound less at the end of the week. If he swears at me for example, I don't pay him a pound for that day. A few weeks back I never thought I'd see him do any thing in the house, but motivated by the extra cash he is actually making an effort. It is also in small chunks which makes it easier to manage. Some of the jobs will only take him a few minutes, but makes a difference for me.
However mine has never really asked for very much money so it may be different for you, maybe different for girls? If her friends spend a lot of money it is hard being the one who hasn't got any. Still, I think it is important to learn that money runs out and it has to be earned. Would she understand if you speak to her when she is calm and feeling happier?
Also, it sounds like she is having a really hard time. Maybe she is just feeling really bad and that is why she is reacting negatively (complaining about hating school and such and such.) I found out recently that my DS has been feeling really crap (emotionally) and when he does he really struggles with his temper and his behaviour in general. Kind of becomes a bit desperate to be allowed to do things with friends, because he is wanting to escape how he is feeling inside...and then if I say No, it all becomes too much. I would listen into what she is saying when she says she 'hates things' because perhaps they hold the reasons for some of her behaviours...?
Good luck, you are not alone 