Thanks for the chance to help. I am an attorney with over 12 years military law
It is true that the Army Regulation on separations requires they provide the soldier
with the opportunity to appear before a board prior to awarding an OTH discharge.
That said, for a reservist, if the Army provides notice, in writing, to their last known address of the pending separation, and the soldier does not respond to this notice, the Army can then award the OTH.
So in your case, the issue will be did your unit exercise due diligence...did they mail notice to your last known address. If they did not? That would be a basis to upgrade the discharge.
I would request a copy of your records. You can do so herehttp://www.archives.gov/veterans/military-service-records/standard-form-180.html
Make sure to request the entire record and not just the DD214.
If they provided you notice, that should appear in your records.
If it is not there? I would apply to the Army Review Board Agency and request they upgrade your discharge.