Request For Test. Upon request by a customer and at no charge, the utility shall make a test of the accuracy of registration of the meter serving the customer, provided that these tests need not be made more frequently than once in 18 months. Customer May Observe. The customer, or his representative, may be present when the meter is tested. Report to Customer. A report of the results of the test shall be made to the customer within a reasonable time after the completion of the test, and a record of the report, together with a complete record of the test, shall be kept on file at the office of the utility for at least 3 years.