Teen angst -cellphone bills

I really don´t know what possessed us to give post paid cell phones to our kids! We have royal fights over how much they spend - so we resorted back to prepaid, but that didn´t work because being so cash strapped, we never had enough to shell out for three cards at the same time. Well, for the second time round we had a serious talk with them and told them that we would go back to the post paid system but they would only have 30 minutes to work with, whatever exceeded that would come out of pocket money. Our big mistake was not following up that threat, I know, I know... be consistent. After some time we had a problem with our eldest who managed to spend more than his father on one single month - he had all the excuses, he had a friend who had had a motorcycle accident and needed help and cheering up, we were out of town and he had to call us (more expensive), he thought that he still had minutes left... then we had a problem with the youngest, she overspent herself incredibly with texting (and I thought she would never learn to read and write when she was in preschool - a few years earlier!), we talked to her and she promised NEVER to text again - not our imposition, though. Because of this, she was without a cell phone while we paid off the bills.Lately we decided to go ahead and change cell phone operator in order to cut costs - this new plan would give my husband and the three kids a 1000 minutes plus fixed phone for free and internet broad band access via fixed phone line for about a third of what we pay nowadays. Yesterday was the day that the migration was complete - also the day that we received three bills - my husband's, the eldest son's and the youngest's cell phone bills with the former operator... to our complete dismay and shock! Our baby girl´s bill (she is 14) was 15 times my husband's! yes - fifteen times - I read on internet that last year the average cell phone bill in the USA was about 78 USD, I asked around my friends at the office today, what kind of bills did their teenagers run up - the answer was between 30 and 50 USD... She managed to spend 831 USD in 30 days - she spent 22 or 23 hours on the phone! interstate fees - her friend lives two states away from us. I mean - what the .....??????

I am still shell-shocked - I have taken the phone away from her - I am threatening to take internet access too - my husband is still at the silent stage...

She said that she needed to talk to her friend (another girl, the same age ) because at least SHE understood her - her acquaintances here apparently do not - they rib her because of her taste in music and because she reacts badly to this - I questioned her on the necessity to be on the phone for over three hours - she said that if she had something better to do she wouldn´t do it, but

because I don't pay for guitar lessons she has nothing to do except spend time on the computer and on the phone - but WHY the phone and not skype or something like that?? Oh, she didn't

have that on her computer and her friend didn't either... besides her friend wasn´t always on the computer (her friend has to SHARE a computer). I reminded her that I am always asking her to help me round the house, but seemingly that doesn't count as something to DO!!

Oh, my poor sweet little baby - brat!

What would you do? Does anyone have any bright idea out there?