(a) A pipeline carrier may not, as to rates, grant a preference or advantage to any customer or subject a customer to an unreasonable prejudice or disadvantage. A pipeline carrier may not establish or maintain an unreasonable difference as to rates, either as between localities served or between classes of service provided under the certificate.
(b) A pipeline carrier may not directly or indirectly refund, rebate or remit in any manner, or by any device, any portion of the rates and charges or charge, demand or receive a greater or lesser compensation for service than is specified in its effective tariff nor extend to any customer served under the certificate any form of contract, agreement, inducement, privilege or facility, or apply any rule, regulation or condition of service except as are extended or applied to all customers under like circumstances.