Maybe a loop hole - but I think we are clutching

Section 27 (4b)

Australian Postal Corporation Act 1989

(4) Australia Post shall ensure:

(b) that the performance standards (including delivery times) for
the letter service reasonably meet the social, industrial and
commercial needs of the Australian community.

.....................................

BUT 26 kind of really covers their butts

26 Commercial obligation
Australia Post shall, as far as practicable, perform its functions in a
manner consistent with sound commercial practice