I would take the copy of your MRI report as well as all records pertaining to your surgery and the follow-up visits since then to another Ortho. Surgeon for a second opinion based on those records. Ask him those questions and if there is anything indicating your surgery didn't take care of the other damaged discs. Perhaps even if he didn't mention it (or perhaps you don't recall- not saying that's the case, but one never knows- I don't care what anybody says, when you're on narcotics, you are NOT yourself nor do you remember everything) he took care of the problem? You won't know until you have a copy of your post op report. And have it looked at by a Dr. That'd be my best advice

And if he says the same things you've suggested, perhaps talk to him about negligence- or better yet, a lawyer.