The Company may cancel this Insurance by giving fifteen (15) calendar days' notice. Such notice shall be given in writing and may be served by registered mail, telex or facsimile transmission, or may be hand delivered to the address of the Insured as stated in the Schedule, Any notice sent by registered mail shall be deemed to have been served seven (7) calendar days after dispatch and any notice sent by telex or facsimile shall be deemed to have been served at the time of dispatch. If this Insurance is so cancelled the Company shall retain only the earned portion of the Premium computed from day to day.