7.—(1) Any timescale with which an investigating authority must comply by virtue of article 5 or 6 may be extended where the investigating authority considers that there are special circumstances which make it appropriate to do so.
(2) Where an investigating authority decides to extend a timescale in accordance with paragraph (1), the authority must write to the person aggrieved—
(a)giving reasons for the extension of the timescale; and
(b)advising of the date to which the timescale has been extended.