50.— Subject to section 97, a person shall not initiate proceedings for the recoupment of any Part 2 inquiry legal costs awarded under this Chapter until the expiration of the later of—

(a) 3 months following delivery by the person of a signed bill of costs referred to in section 51(2)(a) upon the person to be charged, or

(b) if the bill of costs is referred for adjudication under section 51(1) during the 3 months referred to in paragraph (a), until they are finally certified.