"If I agree to the 3,000 I give up all my rights to sue the lawyer." If you are talking about the Lawyers' Fund for Client Protection, you likely should read the material carefully.
It likely is not that you are agreeing not to sue that attorney but that if you do sue and win and get some money, you may have to pay back some of the money you received from the Fund to the Fund.
"What is the best decision to make in this situation?" Without knowing much more information about your situation, no one here can give you any informed guidance as to what you should do.
Likely the only guidance is that you review the specific facts with another attorney to see what legal options you may have.
If the amount in question was for a settlement that is your money, should not have been in the attorney's general fund and should have been in the attorney's trust account. As such you are due that money back in full assuming that the lawyer actually has it or is collectible for it. You need to consult a professional liability (legal malpractice specialist) in your area and determine your rights and obligations under BOTH the terms of the compensation fund and the retainer agreement you signed with the lawyer. as the other attorney that answered suggested. If you are not barred from further recovery, I'd certainly consider taking the compensation they offered, even if you have to pay it back if you make a recovery it may help cover the cost of the legal fees in the meantime. Given the lawyer's conduct so far, they'll take you more seriously if you have representation.
Nothing replaces individual legal counsel specific to your situation and unique fact pattern. This is not that counsel, only general information.