GROUNDS FOR REDUCTION OF SERVICE.

(a) Unless the commission issues a certificate that the present and future convenience and necessity will not be adversely affected, a certificate holder may not discontinue, reduce, or impair service to any part of the holder's certificated service area except for: (1) nonpayment of charges; (2) nonuse; or (3) another similar reason that occurs in the usual course of business. (b) A discontinuance, reduction, or impairment of service must be in compliance with and subject to any condition or restriction the commission prescribes.