(1) Any notice, complaint, decision or other document required or authorized to be served under this Act may be served on any person by sending it by prepaid registered post to his or her last known address—
(a) on any individual by handing it to him or her or by leaving it at his or her residence;
(b) on any firm by handing it to any partner, or by leaving it at the principal place of business of such firm;
(c) on any limited company by handing it to an officer of the company, or by leaving it at its registered office; and
(d) on the Manager of the workplace, even though it is a limited company, in the manner referred to in paragraph (a), (b) or (c).
(2) Any such document intended to be served upon the Manager of the workplace may be addressed to “the Manager” at the proper address of the workplace without further name or description.