What can I do about this?

I was thrown out of university (uk) for having a mental illness 5 years ago. My work was good and I was getting my dissertation together. I had to defer and restart the third year as I was in hospital with my illness for a month. When I went back to uni the attitude of my lecturers was terrible and one of them accused me of not being ill and playing a game. Another one was not interested in my dissertation and eventually threw me off the course. I was not strong enough to fight them at the time but now I feel they should not be able to get away with this. I mean if I had broken my leg they probably would have been supportive because my illness was mental they didnt understand I feel discriminated against but dont know how to go about taking this further as it was so long ago. I though universitys would be more understanding in this day and age.