When there is more than one route between given points in North Carolina, and freight is routed or directed by the shipper or consignee to be transported over a shorter route, and it is in fact shipped by a longer route between such points, the rate fixed by law or by the Commission for the shorter route shall be the maximum rate which may be charged, and it shall be unlawful to charge more for transporting such freight over the longer route than the lawful charge for the shorter route.
N.C. Gen. Stat. § 62-145