No charge may be imposed by any such company in any case where a subscriber requests a total disconnection of service. No charge that exceeds the cost to the company may be imposed by any such company in any case in which the subscriber requests a downgrade of service. The subscriber, after the date of his request for disconnection or downgrade, shall not be required to pay for any service in the case of a total disconnection or any service option requested to be eliminated, unless the subscriber prevents the company from disconnecting service within a reasonable time.