Any appearance, application or act required to be made or done by any person before or to a competent authority (other than an appearance of a party which is required for the purpose of his examination as a witness) may be made or done on behalf of such person by a legal practitioner or by an official of an Insurance Company or a registered Trade Union or by an Inspector-cumFacilitator appointed under sub-section (1) of section 122 or by any other officer specified by the State Government in this behalf, authorised in writing by such person, or, with the permission of the competent authority, by any other person so authorised.