In a case where—
the building control authority may pay to the person to whom the section 36 notice was given such amount as appears to them to represent the expenses reasonably incurred by him in consequence of their having given him that notice including, in particular, his expenses in obtaining the report.
Subject to subsection (3) below, if a person to whom a section 36 notice has been given gives notice under subsection (1)(a) above, then, so far as regards the matters to which the section 36 notice relates, the reference to 28 days in section 36(3) above shall be construed as a reference to 70 days.
Notice under subsection (1)(a) above shall be given before the expiry of the period of 28 days referred to in section 36(3) above, or, as the case may be, within such longer period as the appropriate court or tribunal allows under section 36(3); and, where such a longer period has been so allowed before notice is given under subsection (1)(a) above, subsection (2) above does not apply.