66 Pa.C.S. § 1502

No public utility shall, as to service, make or grant any unreasonable preference or advantage to any person, corporation, or municipal corporation, or subject any person, corporation, or municipal corporation to any unreasonable prejudice or disadvantage. No public utility shall establish or maintain any unreasonable difference as to service, either as between localities or as between classes of service, but this section does not prohibit the establishment of reasonable classifications of service.