Carriers should adjust claims for damages resulting from misrouting. Where a carrier admits responsibility for billing, forwarding, or diverting a shipment over a higher rated route than that directed by the shipper or otherwise available, the misrouting carrier should refund the difference to the shipper (or reimburse the delivering carrier, as the case may be). Where the misrouting carrier alleges justification for using the higher rated route, the Board may, at its discretion and upon appropriate petition, determine or express an advisory opinion on the lawfulness of such routing. This interpretation must not be used to evade or defeat tariff rates or to meet the rate of a competing carrier or route, nor to relieve a shipper from responsibility for routing instruction. Damages caused by misrouting are not overcharges.