(1) Where Regulation 8(6) does not apply and the Commissioners and the competent authority of each relevant Member State decide to accept a complaint, the Commissioners shall, with the competent authority of each relevant Member State, endeavour to resolve the question in dispute by mutual agreement, subject to paragraph (5), not later than -
(a) subject to subparagraph (b), 2 years from the date of the last notification of a decision to accept the complaint, whether that decision is made by the Commissioners or a competent authority of a relevant Member State, as the case may be, or
(b) the end of any extension of the period referred to in subparagraph (a), where the Commissioners or the competent authority of a relevant Member State, as the case may be, make a request to the competent authorities of the other relevant Member States (including the State, as the case may be) for an extension of not more than 1 year of that period and provide written justification for such an extension.
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