(3) A decision of the Commission rejecting a proposed tariff shall— (a) be in writing; (b) state the reasons for the rejection; and (c) be made available to the provider. (4) Where the Commission approves a new tariff, a licensee shall notify its customers of the new tariff through publication in two local daily newspapers with nation wide circulation or through any other method as the Commission may determine and shall in the notice provide for a grace period of not less than fourteen days before implementing the new tariff. (5) A licensee who contravenes this Regulation commits an offence. 10. Investigation of tariffs. (1) The Commission may on its own motion or pursuant to a complaint made under this regulation investigate any tariff set by a licensee. (2) A complaint about a tariff brought under paragraph (1) shall— (a) Be in writing; (b) Specify the name and address of the complainant; (c) State the interest of the complainant; and (d) State the reasons why the tariff should be investigated. (3) Where after investigation, the Commission is of the view that the tariffs should adjusted, it may adjust the tariff. Provided that where the Commission intends to adjust the tariffs after investigation, the Commission shall notify the licensee and give the licensee twenty days to respond to the intended adjustment. 11. Promotions and special offers. (1) The Commission may from time to time issue guidelines on promotions and special offers.