I wonder if the school has a judgment against you. It is leaving you with an amount that probably equates to what would be exempt from garnishment. As to lack of notice and appeal, read the employee handbook on these subjects. Unless there is some employee rule or contract to the contrary, the school probably can do what it is doing. I also wonder what you mean by being "booked to work", and whether you have a contract that would create monetary damages if you left that job for another. Of course, if you are a regular employee for a university, then you probably have benefits which you may want to protect rather than leave the job. Your choices are difficult, and you might be best served by obtaining the services of a lawyer in your area who is experienced in employee rights.
These comments do not constitute legal advice. They are general comments on the circumstances presented, and may not be applicable to your situation. For legal advice on which you may rely consult your own lawyer.