I would ask first if there was some type of payroll processing error. Then if they say no, you can ask what is up and tell them your story. No sense starting fires without getting as much information prior to the burning that you can for your sake. If there is an error it should be easily remedied. If not ask for something in writing enplaning the difference.
The employer does not have to tell you that your pay is going to be reduced( although this would be morally and ethically the right thing to do). Your pay check reflecting the change is the notice. You at this point have the choice to stay or go. You can collect unemployment because it it a life changing event. You're better off getting another job than collect cause you'll go deeper in debt.states can't force a company to pay x amount per hour so long as they meet the minimum wage.
I would report this to business management agency or bureau of investigation. Make a copy of the email. Write down the dates when all of this occurred. Better to be safe than sorry.
Any other suggestions should I go to the unemployment office because h.r just said to bad should I have not had to sign something after my transfer