Discriminated against

I was very sick and couldn't write my examination, I produced my medical certificate to the institution which stipulates that I wasn't in no condition to write. the committee has come back and declined my application saying they have no dates available for me to write my examination, they are telling me that I have to re register the module next year and buy new text books, pay for the module and rewrite my exam. now this is unfair because my colleague had once suffered the same fate but the committee approved her application, I strongly feel that I am being discriminated against and I have exhausted my options. The deferral ruling stimulates that if i cannot write due to medical reasons I have the right to apply for deferral but I see that this deferral is not just for anybody!!!