1. a. A common carrier subject to this chapter shall not charge more for the transportation of persons or property than a fair and just rate or charge.

 b. A common carrier shall not:

 (1) Charge more for the transportation of persons or property for a shorter distance than for a longer distance in the same direction on the same route.
 (2) Charge more for a through rate than the aggregate of the intermediate rates.
 2. However, upon application by a common carrier, the department may in special cases and after investigation prescribe the extent to which the carrier is relieved from compliance with this section.