(4)
In no case may the head of an agency—
(A)
enter into a contract for property or services using procedures other than competitive procedures on the basis of the lack of advance planning or concerns related to the amount of funds available to the agency for procurement functions; or
(B)
procure property or services from another agency unless such other agency complies fully with the requirements of this chapter in its procurement of such property or services.
The restriction contained in clause (B) is in addition to, and not in lieu of, any other restriction provided by law.