Released on early and returned for error by State?

My son was released from prison for good behavior in 1998. He had a job and followed all the rules he was given. He was out for one year. On april 28th 1999 he was returned to prison because the state said they released him to soon. I have written to everyone from the First lady to State representatives. I recieved directions on who to write next. I am not upset about the time he served, but he came out a responsible citizen. Who supported his child worked everyday, never late in reporting to the half house. Even the halfway house offered to write a letter on his behalf. I would like anyone to explain to me what recourse does a person have when something like this happens. Who can a person turn to. Should I hire a lawyer. I did write the judge who sentenced him and he is retired. I told the court report and we did found a error where the paper was changed. Help me found our where to go next.