6.—(1) Subject to paragraph (3), the Secretary of State may enter into an agreement with persons (an “advance payment agreement”) under which, on such terms as may be provided by the agreement, charges for a motor vehicle to be used or kept on the crossing may be paid in advance.
(2) An advance payment agreement may relate to such use or keeping on such number of occasions, or during such period, as may be provided by it, and may provide for a reduction in the charges set out in the applicable charging regime.
(3) An advance payment agreement offered by the Secretary of State must be offered on the same terms to all persons seeking to enter into such an agreement.