How can I fight an Erroneous Enlistment Discharge?

My son expressed an interest in the Air Force while he was in high school. He spoke to a recruiter and was told that due to his ADHD he needed to be off of his ADHD medication for 1 year before entering BMT. In June 2009 he was taken off the meds. After a couple of visits with psychologists at MEPS in Portland, Oregon, he was given a waiver and went to BMT in November 2010. He completed BMT and went to tech school for Security Forces, not his first choice since he had high scores and qualified for several technical fields, but its what they gave him. He was tentatively assigned to a Nuclear base in Wyoming and had to go through the clearance process. During the clearance process they realized that his waiver should have been sent to the Surgeon General for approval which it wasn't and that the 1 year med free rule had changed to 2 years med free. It was determined that due to the Air Forces oversight my son was erroneously enlisted in the Air Force. He was sent to an out processing unit at Lackland AFB and was recently served papers for discharge. The papers indicate that the discharge is for Erroneous Enlistment with a re-enlistment code of RE-2, it also states that he is not eligible to re-enlist in the Air Force. The messed up thing is that last week he went over the 2 years med free mark. He wants to stay in and is speaking with legal council to fight the discharge. We have also initiated a congressional inquiry into the matter. I am wondering if anyone has any advice n the best way to approach this and what options may be available to my son.