6. The Director may amend a legal aid certificate —
where it appears to him that there has been some error or mistake in the certificate;
when, in the opinion of the board, it has become desirable either for the certificate —
to be extended to other proceedings, being part of the same action, cause or matter to which the certificate relates, or proceedings for the enforcement of any such order or agreement as is referred to in regulation 14(3); or
not to extend to some of the proceedings in respect of which it was issued; or
when an aided person desires to change the solicitor who is acting for him or the solicitor assigned by the Director to act for the aided person discharges himself from acting for the aided person.