This subtitle does not preclude the Commission from entering into a collective bargaining agreement with an exclusive representative that requires an employee, as a condition of employment, to pay a maintenance or service fee as a contribution towards the cost of the negotiation and administration of the collective bargaining agreement. A maintenance or service fee under subsection (a) of this section may not exceed the annual dues paid to the exclusive representative. Before the Commission discharges an employee who fails to pay a maintenance or service fee, it shall give the employee: written notice of the delinquent payment; and adequate time to correct the delinquency. If the Commission and an employee are unable to resolve any issue relating to the payment of a maintenance or service fee, the issue shall be submitted to an umpire in accordance with § 16–317 of this subtitle.