The Council shall fix the compensation of the members of Council, the Mayor, and the Auditor for the ensuing term of office at a meeting held not later than thirty days prior to the last day fixed for filing as a candidate for such offices. The compensation of members of all boards and commissions established by or under the Charter shall not be increased or diminished during the term of office for which such member was appointed, provided, however, that the compensation of any such member may be decreased during such term upon the written consent of such member, which consent shall be filed with the Clerk of Council. The compensation of all other officers and employees of the Municipality may be increased or diminished at any time by action of the Council.