working related issue

To to give you a bit of my background, I have been with this company for over 5yrs, and have never had an issue like this before. I always show up to work on time and cover for others when necessary. I am currently in nursing school out of state and my current employer knows this and have never had an issue until today.

Issue:

I received a call today from said employer stating that if I do not work 32hr by the end of this month I will have to resign. I asked why I needed to work 32 hrs and they stated it was protocol. I said that I was currently at school finishing a nursing fellowship opportunity and that will be home at the end of the month to work. The employer did not care that I was out of state and repeated that if I did not give 32hrs of work that I will resign at the end of the month. To make matters worse, this was not my manager calling me.

I called HR to speak with the recruiter that handles all of the CNA issues and she stated that the person that called me should not have called me about this issue and that I should take it up with my manager of my department. I told her (HR) that while in school I currently work on breaks or when I come home and have been doing this for the past two years. She said that this should not be an issue, and for them to change policy without your knowledge is crazy and uncalled for.

I left a message for my manager to call me back. This has made me so upset because I love my job and for this to happen today makes me feel like I mean nothing to my employer.

What would you do in my situation? I feel threatened and that they are forcing me to quit my job if I do not work the said hours. The person that called me was very unprofessional and did not care what I had to say. To make matters worse, more than ten people that I used to work with have left this department because of the moral and disrespect they have been receiving the past few months.