law: 54. Salary and allowances of the Commissioner.
  The Commissioner shall be paid out of the Municipal Fund such monthly salary and such monthly allowances, if any, as may from time to time be fixed by the Central Government and may be given such facilities (if any) in relation to residential accommodation, conveyance and the like as may from time to time be fixed by that Government:
  Provided that the salary of the Commissioner shall not be varied to his disadvantage after his appointment.