17.—(1) It shall be for the Department to determine—
(a)a question whether—
(i)an increase of disablement pension under section 104 of the Contributions and Benefits Act, or
(ii)a further increase under section 105 of that Act,
is to be granted or renewed and, if so, for what period and of what amount;
(b)a question how the limitations under Part VI of Schedule 7 to the Contributions and Benefits Act on the benefit payable in respect of any death are to be applied in the circumstances of any case;
(c)a question arising under regulations made under section 5(1)(i) of the Administration Act.
(2) The Department may review any determination given by it on any question referred to in paragraph (1) where—
(a)new facts have been brought to its notice; or
(b)it is satisfied that the determination—
(i)was given in ignorance of some material fact,
(ii)was based on a mistake as to some material fact, or
(iii)was erroneous in point of law.
(3) A decision of the Department on a question under section 70(7) of the Contributions and Benefits Act or on any question which by virtue of regulations falls to be determined by the Department in its discretion may be given so as to have effect with respect to a period before the date of the decision; and it may at any time and from time to time reconsider the exercise of its discretion with respect to such a question and decide it again with such other effects as may seem to it to be proper in the circumstances of the case.