I have my two sons in a day care facility and haven't seen anything like this -- nor am I understanding any of it.
I don't know your set up based on what your wrote, but when we enrolled, we received a statement that says how much it is per child to attend based on a 5 day week, a 4-day week, etc. This is a monthly charge. It includes if the center is closed, if I have to pull my sons out for any reason (they're sick), etc. The monthly amount does not fluctuate. I know what I'm paying each month until one of them moves to a new level/room. There have been a few fees tacked on here and there for extra supplies ($5 tops and only once in a while) but I'm given a heads up prior to that hitting my account.
I also signed an agreement that this is what I would pay, this is what they would provide, etc. It doesn't seem that your provider can adjust fees based on a whim or an accountant's findings when looking at the books. I would fight this for 2008. It's not what you agreed on (or at least as far as I can tell based on your post.) If they want to make a fee change starting Feb 1, great. But that needs to be communicated prior to raising fees.