(6)No insurer to whom the notice referred to in sub-section (2) [or sub-section (2A)] [Inserted by Act 58 of 1960, section 3 (w.e.f. 26.12.1960).] has been given shall be entitled to avoid his liability to any person entitled to the benefit of any such judgment as is referred to in sub-section (1) [or sub-section (2A)] [Inserted by Act 58 of 1960, section 3 (w.e.f. 26.12.1960).] otherwise than in the manner provided for in sub-section (2) [or in the corresponding law [* * *] [Inserted by Act 58 of 1960, section 3 (w.e.f. 26.12.1960).] of the reciprocating country, as the case may be].