Can we fight a reduction of two grades after 4 1/2 years?

My husband was demoted from SGT to PFC in 2006. He had an inefficiency board for 2 counts of fraternization. We have looked about information on this and there are many problems. First his board was biased since 3 other members of the board had done the same thing. One of them with the same girl. The only paperwork we have is one negative NCOER. There are no reduction orders, plus he was told it was only a punishment of PFC for 6 months then SPC for 6 months. He did not make SPC until a year later, and has been fighting for his SGT since. We have witnesses who are willing to testify that his chain of command didnt care about him and gave him a very hard punishment on purpose. With other units that he has been in he has not had one issue. With it being this long can we still fight this and try and get his rank back? The two girls who were involved got demoted but while they where in Iraq they continued to do this act with of soldiers and one got married to the Sgt Maj and she made SGT, plus she was demoted to PVT and accussed my husband of rape was founded false. What should we do?