The public utilities commission may provide instruments for, and carry on, the examination and testing of all appliances used for the measurement of any product or service of a public utility or for the examination and testing of any devices or appliances of such public utility used for testing for accuracy any appliance used for the measurement of any product or service of such public utility. Any consumer or user may have any such appliance tested upon payment of the fees fixed by the commission. The commission may establish reasonable fees to be paid for testing such appliances on the request of the consumers or users. The fees shall be paid by the consumer or user at the time the request is made, but shall be paid by the public utility and repaid to the consumer or user if the appliance is found commercially defective or incorrect, to the disadvantage of the consumer or user.