30. Service of a document upon a trade union shall be effected by —
(a)
leaving it with the president, the secretary, the treasurer or other officer of the trade union;
(b)
tendering it to the president, the secretary, the treasurer or other officer of the trade union;
(c)
leaving it with a person apparently above the age of 14 years at the registered office of the trade union, or where the trade union has filed an address for service, at that address; or
(d)
posting it in a prepaid registered letter to the secretary of the trade union at the registered office of the trade union or, where the trade union has filed an address for service, at that address.