R12274.53 DATA USAGE!!!HELP

I have a contract of data only, my bill is every month R200 for 3 years now. This month it was deducted R12274.53, this data card is only in my computer and I am the only one who use it, I don't go on you tube ,facebook or any videos, it is only used for emails. Never ever have I gone over my limit of R150, but this month when I phoned in they told me there was no more limits on contracts and they send out sms to their costumers.My stick is in a computer how the hell must I read an sms on it. So I told them that I was not informed of the change in this contract,but they can check my record I have never used so many data in my life!!! Please Please can someone tell me what to do because I have 3 kids and there is no way in my life that I can afford it. I feel like hanging myself!!!! How must I cope???? This is outrageous. They say it can take up to 7-14 workdays before they can help you and in the meantime what must I do ??? I seriously don't have that sort of money laying around..Help me anyone Help me...I am in a overdarft I have never been so depressed in my life...I don't know what to do PLEASE