Unfair labor practices

Hi, am Jyselle. I am working at a call center industry. I was promoted as a manager last May 2011. Before my regularization November 2011 the company need to lessen number of officers due to over staffing reason why my contract as Team manager was terminated. However, i did not go back to the old position as Agent but instead I was still managing people but as a TL intern. This means I still act as a manager but being paid as an agent. No extra allowances etc. I did this for 7months. This is because of our management promise that if a Team Lead post is needed again they will hire me immediately. But that did not happen. I felt like i was being used by the management in out account and I wanted to file a case against them. Is this a valid ground? Thank you

were you being paid the same as before you became a probationary manager?