Whenever a customer desires discontinuance of service, he shall notify the utility at its local office of this desire and of the date on which service is to be discontinued, sufficiently in advance of the date to provide a reasonable time for the utility to obtain a final meter-reading. This section shall not apply to any case where a customer has entered into a contract with the utility to take service from the utility for a definite period of time specified or provided in the contract.
('75 Code, § 6.19)