Misrepresentation on hire?

I was hired on to my current position as a store manager in waiting. During the interviews with the recruiter and district manager I was told I would be guaranteed 40 hours a week until I was placed in my own store and that could take up to 90 days. I have now worked for the company for 8 months and still haven't been given a store, the entire time I have been waiting I have worked in a local store under a new manager that was hired the week before I was and she has started cutting my hours. As low as 28 hours per week. I ask her about it and she simply States she doesn't have the payroll. I ask dm about it and even though I am a manager candidate I am still considered a full time employee and that means that my hours could range from 28 to 40 per week. I would have never accepted the job offer if I weren't guaranteed 40 hours. Is this considered misrepresentation on hire because they promised me things to get me to come work for them and now they are not upholding their end?
Latest news is that I go check the schedule and now my job code has been changed, I have been demoted to an assistant manager. I ask the store manager why my code is changed and her answer was I don't know the district manager most have done it. Can they demote me with out even talking to me about it? Seems very unprofessional and unethical. Thank you for any reply.