Am I entitled to revoke the power of attorney I granted to my neighbor to act on my behalf concerning a piece of land I acquired in my name—based on an agreement between us—since he has not fulfilled his agreed-upon obligations, in order to compel him to transfer ownership of the land or compensate me financially, knowing that this land prevents me from receiving government housing support?

If the land registration in another person's name was authorized by the granting states, then you have the right to claim the agreed-upon amount and seek redress for damages, and to sue the person, but you do not have the right to revoke the power of attorney. However, your employment at a usurious bank is not permissible. If the registration was not authorized, then you have no right over it, and you must return what you took, and both of you should refer to the responsible authorities or people of knowledge.