Ohio Rev. Code § 4905.22: Service and facilities required - unreasonable charge prohibited.

Every public utility shall furnish necessary and adequate service and facilities, and every public utility shall furnish and provide with respect to its business such instrumentalities and facilities, as are adequate and in all respects just and reasonable. All charges made or demanded for any service rendered, or to be rendered, shall be just, reasonable, and not more than the charges allowed by law or by order of the public utilities commission, and no unjust or unreasonable charge shall be made or demanded for, or in connection with, any service, or in excess of that allowed by law or by order of the commission.