(1) If the Commissioner believes on reasonable grounds that a certified diesel user has contravened a condition of registration, the Commissioner may, by written notice to the user—
(a) vary a condition of the user's registration; or
(b) suspend the user's registration for a period starting on the date of the notice and ending—
(i) on a date specified in the notice, or on the revocation of the suspension, whichever is earlier; or
(ii) if the notice of suspension specifies any condition for the revocation of the suspension—on the revocation of the suspension following the satisfaction of any such condition, or on a later date (if any) specified in the notice.
(2) The Commissioner may, by written notice to a certified diesel user whose registration has been suspended, revoke the suspension on application by the user or on the Commissioner's own motion if the Commissioner is satisfied on reasonable grounds that—
(a) if the notice of suspension specified any conditions for the revocation of the suspension—the user has satisfied any such condition; or
(b) in any other case—such revocation is justified in the circumstances.
(3) The variation of a condition of registration, suspension of registration or the revocation of such suspension—
(a) shall be entered by the Commissioner on the Diesel Users Register on the date of the relevant notice, or on such later date as is specified in the notice; and
(b) takes effect on such registration.