The salaries and allowances payable to, and the other terms and conditions of service (including pension, gratuity and other retirement benefits) of, the Chairperson, Judicial Member and Expert Member of the Tribunal shall be such as may be prescribed:

   Provided that neither the salary and allowances nor the other terms and conditions of service of the Chairperson, Judicial Member and Expert Member shall be varied to their disadvantage after their appointment.