16.—(1) The Department may review any certificate of total benefit if the Department is satisfied that it was issued in ignorance of, or was based on a mistake as to, some material fact or that a mistake (whether in computation or otherwise) has occurred in its preparation.
(2) On any such review the Department may either—
(a)confirm the certificate; or
(b)issue a fresh certificate containing such variations as it considers appropriate,
but the Department shall not so vary the certificate as to increase the total benefit.
(3) In any case where—
(a)one or more relevant payments have been made; and
(b)in consequence of a review under this paragraph, it appears that the aggregate amount so paid exceeds the amount that ought to have been paid,
the Department shall pay the intended recipient an amount equal to the excess.