" Except as provided by the following provisions of this section, any provision in an agreement (whether a contract of employment or not) shall be void in so far as it purports - (a) to exclude or limit the operation of any provision of this Act or; (b) to preclude any person from presenting a complaint to, or bring any proceedings under this Act before, an industrial tribunal."
"(d) to any agreement to refrain from presenting a complaint under section 67, where in compliance with a request under section 134(3) a conciliation officer has taken action in accordance with that subsection; (e) to any agreement to refrain from proceeding with a complaint presented under section 67 where a conciliation officer has taken action in accordance with section 134(1) and (2); (g) to any agreement to refrain from instituting or containing any proceedings before an industrial tribunal where a conciliation officer has taken action in accordance with section 133(2) or (3);"
"to any agreement to refrain from instituting or continuing any proceedings specified in section 133(1) (except (c)) or 134(1) before an industrial tribunal if the conditions regulating compromise agreements under this Act are satisfied in relation to the agreement."