Momentum don't want to pay

I have been permanently boarded due to disability. I have logged a claim with Momentum for disability but was declined. I was advised that my option was for specific disability. According to them dystonia is not a specific disability. I however opted for the comprehensive option when I joined but was forced to take the specific option by Momentum as I was a student at that stage. This is really unfair treatment by Momentum. I had to take that option under duress, just because I was a student.