Can I Set Aside a Conviction Based Upon a Plea Deal I Didn't Understand

My question involves police conduct in the State of: Pennsylvania

5 years ago I was charged with simple assault and making terroristic threats. The ADA approached myself and my public defender, the victim was actually with me and a witness willing to testify to this... The ADA told me that I would qualify for ARD if I plead guilty to terroristic threats instead of simple assault. Neither my lawyer or the ADA notified me that it was a higher level misdemeanor than simple assault. After my plea was entered and it came time for the ARD I was told I didn't qualify... All of this was oral, my lawyer did not receive anything in writing, I did not find out it was a worse charge I plead guilty to until a few months ago. I would have loved to take the simple assault if I knew it was a lesser charge and my ARD would be denied. I believe I was misrepresented and only now do I have the knowledge I was lacking years ago. The victim of the crime and one other person witnessed this promise and are willing to testify. Do I have any options for recourse? Is it possible to get a retrial or my plea changed to simple assault since their oral contract was broken? Or is it possible to get the promise of ARD enforced? Any help is appreciated. Thank you.

Why did you choose to plead guilty to the terroristic threat charge after you were rejected for ARD?

ARD is entirely discretionary on the part of the court and really the DA determines who is eligible. You can make a motion over the DA's objection but it's unlikely it will be approved. You can retract a preliminary guilty plea prior to trial when a plea bargain falls through.

I didn't. I was told that I didn't qualify after the plea was entered and the trial was concluded. I would have never chose terroristic threats if I knew.

Something is NOT right in this story. It doesn't work that way. You don't enter a plea to get into ARD. You usually do waive your preliminary hearings. If accepted you have a special ARD hearing. If you're not accepted, that just turns into the arraignment. In fact, in PA misdemeanor cases, you don't even enter a plea at the arraignment. They just ask you how you intend to proceed: guilty plea, bench trial, jury trial, and schedule your next hearing (if you state you're going to plead guilty, they'll often send you to the PSI in the interim).