There is no way of knowing whether a settlement amount is fair or reasonable based solely on the few facts you provided. I'm not suggesting that you should post more info here, because, the truth is, there are soooo many factors that contribute to evaluating a case for settlement purposes that it could not really be done in this kind of forum.
Just to give you an idea of what I mean, here are just a few relevant things that an attorney would need to know: Did the carrier authorize the surgery? What kind of surgery? What kind of pain/problems does the neck injury cause? Do you have any pre-existing neck problems? Has the defense alleged any fraud against you? Have you already exhausted your wage loss benefits? How old are you? Are you a Medicare recipient? What permanent work restrictions did your doctor(s) assign? Are you working? Why $36k (is it all for future medical, or is some allotted to wage loss or other benefits)? What other future medical care are you reasonably likely to need?
This is just a sample of factors that would need to be considered. If you don't trust your lawyer, go talk to another one. Most comp lawyers will give you a free initial consultation. If the new lawyer thinks that you should get more for a settlement and that there is some way out of the settlement you described, then you can change lawyers (but be aware that the first lawyer would still have a claim of lien for fees and costs for whatever benefit (s)he brought to your case thus far).