Will this hurt my case?

Hi, i was dismissed from my job in november. i was employed for 4&1/2 yrs, i have still not had my appeal with the hr dept. i have been adv by my union rep that they will uphold the original decision, as the company always does. I have been adv by the union that i have a strong case for unfair dismissal. however this does not help me now. would it be detrimental to my case if i sent my hr dept an email outlining the info i have showing the dismissal to be unfair and state a sum i would be happy with at this point. returning to my job wouldn't be a possibility im afraid. any help or suggestions would help enormously. thanks :)