(1) Without prejudice to the powers of courts of appeal and revision, any custody order, supervision order or probation order may be amended by the competent authority which made such order in respect of the person named as custodian, supervisor or probation officer and such other details as may be deemed necessary:
Provided that in the case of an order committing a child to an institution, no such order shall be amended except in relation to the period of duration, such amendment being by way of extension on the period only:
Provided further that in case of emergency and for immediate necessity a committal order may be varied by way of charge in the institution to which the order relates, such variation being subject to confirmation by the Chief Inspector.
(2) Clerical mistakes in orders passed by a competent authority or patent errors arising therein from any accidental slip or omission may, at any time, be corrected by the competent authority either on its own motion or on an application received in this behalf.