Is there a way to sue or file a complaint against a DA?

My son was killed in a car driven by an intoxicated young woman. After stating multiple times, I did not want a plea bargain and that I wanted it to go to trial. The DA decided to take one reducing. The original DUI causing death to a reckless driving alone. How can the State totally dismiss my son’s death in the final charge? This can't be legal. The young woman was sentenced two weeks ago to a 4 month sentence. I am outraged and devastated. We were told to prepare statements and have family and friends submit letters on my son’s behalf. We did all of this and I wonder for what the DA knew going in she would not serve more than 6 months with this ridiculous plea deal we however were left to find out after. I realize the judge can only sentence for the charge set before him, but this is unbelievable to me. I assure you there were no holes in this case. I have the police report. There was timely blood work done that concluded she was over double the legal limit of alcohol. She admitted to smoking marijuana the previous day, was conscious on the scene and most importantly my sons life was lost. I am left wondering what happened. Could the judge have refused the case and said that the death would have to remain on the charge? If not than is this actually legal for the State to do and what are my options now? I can't help but to think that the DAs office has to be accountable to someone when they totally screw up. Any info on this matter would greatly be appreciated.