Employees and agents of the District other than duly appointed contracting officers shall not execute contract modifications or:
A contractor shall be bound by the terms of the written contract and written contract modifications signed by the contracting officer. A contractor shall not rely upon any written or oral statements or directions of employees or agents of the District, other than the contracting officer, for authority to perform work, alter schedules or specifications, or any other action that would normally require a written contract modification.
The District shall not be responsible for any costs incurred by a contractor for any additional work or other actions by a contractor outside the scope of the written contract and written contract modifications signed by the contracting officer.
D.C. Mun. Regs. tit. 27, r. 27-3602