You will have to sue the organization you gave your money to in order to get your money back. (It wasn't a government organization, though they may have claimed to be.) Only the Seminole Tribe itself determines who its members are, and you will have to contact them directly. There is more than one nation claiming to be of seminole descent and claiming the name "Seminole," but I assume you mean the large tribe based mainly in Tampa. You can find information on how to contact them at semtribe.com.