Took much more money than they promised to take

I do not make a lot of money, but I have been told that they can slow down the payment for school. When I checked my account, they took $750 instead of the promised $70. I called them again, and they said there is nothing they can do, the system works automatically. And as soon as they hanged up, I saw that they took even more money! I am not able to pay that sum right now!