A mediation agreement was signed, can I go back on it and refuse due to settlement amount has changed since signed?

I cannot give you a definitive answer to your question as to whether you can "go back" and refuse to settle after signing a mediation agreement. To answer the question a lot more information would be needed including, but not limited to: what the mediation agreement specifically says; does the release include any significant differences from what was agreed to in the mediation agreement; and why some of your medical bills were not included as part of the settlement. Generally, a mediation agreement is an enforceable agreement and you are bound by its terms. If you refuse to sign the release the other side can go to court and ask the Court to have the mediation agreement enforced. However, as noted, this is the general rule. There are some exceptions and you might be able to void the mediation agreement. Without knowing more about your case, the mediation agreement and the release, I cannot comment whether you are bound by the mediation agreement. I would strongly suggest talking to your attorney about why your other bills were not included and whether there is a way to void the mediation agreement and permit you to receive more money.

You may be able to refuse, but it's doubtful.

What does your lawyer tell you? You may be stuck.