IS THIS CASE APPLICABLE FOR THE WRONGFUL DISMISSAL

I started with this company thirteen years ago with the job title Technical Support Manager (Grade 21 - exempt employee). Since then, I have been promoted to Grade 22.
Three years ago I was transferred to another team under a different director. My director prior to the transfer, told me that my job responsibilities, grade level and title would not be change. However, I never saw any official paperwork between two directors regarding my transfer. My current director gave me work that did not fit my experience or title. His group had some other positions for Grade level 22 employees, but he never gave me an opportunity to try those positions. I was assigned to do installation – a job that is normally done by non-exempt Grade 14 employees. I was expected to work overtime without extra compensation. In my opinion, my director was trying to take advantage of the fact that I am an exempt employee and do not receive overtime pay. I thought I was being treated unfairly and complained to him.
A few months ago, my director tried to demote me to a Grade 14 employee to match the work he was assigning me. I objected and reported the incident to the Human Resources Department. HR told me to wait for some further action from my director but my issue was never resolved. Recently, he hired a new Grade 14 employee to perform the same job. Shortly afterwards, I was given notice that my job position was no longer needed and I was given a severance package. He told me the layoff was due to business reasons. I went to HR department and the HR director told me that my grade level and job title in installation was eliminated without cause. In my opinion, the Grade level 22 job never existed in the installation team. However, I feel that I am being wrongfully dismissed. I want to know if whether I have a case and what options are available.