ACL doesn’t talk about fault finding, only about goods being of acceptable quality (54) and of goods being fit for purpose (61) and contracts can’t remove provisions of ACL (64) or limit the sellers liability (64A) and a whole bunch of other things businesses hate... You can read it at
https://www.legislation.gov.au/Details/C2015C00327/Html/Volume_3#_Toc424644337
(or search for ACCC Ora consumer groups interpretation of ACL which may be more easily digestible)
The take from ACL is that a factory warranties against defect must meet the form and content as prescribed by ACL (or the bureaucrats that administer such things). And I doubt an acceptable factory warranty (as ACL would see it) would place the fault finding cost burden on the consumer... I don’t recall reading such conditions within Holden own warranty documentation, so if it ain’t written it doesn’t exist. Even if it’s written, it's against ACL so in essence such factory warranty clauses don’t exist.
You have a defect, and you’ve taken it to be repaired multiple times so it must rise to the classification of major fault by now... If so, be done with these clowns and simply ask (in writing) for a full refund as is your right under ACL. They may quickly change their tune and decide it’s worth it to investigate and find the fault and rectify it...
So speak to BCS again and outline your situation in the above frame. You have a fault and you can’t spend $1000’s to try and localise where the fault is. One dealer has witnessed the fault and the dealers are the experts so they should get on with resolving the fault in a reasonable time frame without sucking $$$ from you. But instead the fault isn’t being looked at because they have no clue and want you to spend $$ so they can meet the manufacturers illegal process. .
PS: it may seem tempting to simply replace the lock @ $160 but if that won’t work, you’ll be chasing your tail spending $$. Push the dealer to do his job and fix the defect (what ever it is... if he can’t, get a full purchase price refund and buy something else and be done with Holden... it’s just a car)...
54. Guarantee as to acceptable quality
(1) If:
(a) a person supplies, in trade or commerce, goods to a consumer; and
(b) the supply does not occur by way of sale by auction;
there is a guarantee that the goods are of acceptable quality.
(2) Goods are of acceptable quality if they are as:
(a) fit for all the purposes for which goods of that kind are commonly supplied; and
(b) acceptable in appearance and finish; and
(c) free from defects; and
(d) safe; and
(e) durable;
as a reasonable consumer fully acquainted with the state and condition of the goods (including any hidden defects of the goods), would regard as acceptable having regard to the matters in subsection (3).
(3) The matters for the purposes of subsection (2) are:
(a) the nature of the goods; and
(b) the price of the goods (if relevant); and
(c) any statements made about the goods on any packaging or label on the goods; and
(d) any representation made about the goods by the supplier or manufacturer of the goods; and
(e) any other relevant circumstances relating to the supply of the goods.
(4) If:
(a) goods supplied to a consumer are not of acceptable quality; and
(b) the only reason or reasons why they are not of acceptable quality were specifically drawn to the consumer’s attention before the consumer agreed to the supply;
the goods are taken to be of acceptable quality.
(5) If:
(a) goods are displayed for sale or hire; and
(b) the goods would not be of acceptable quality if they were supplied to a consumer;
the reason or reasons why they are not of acceptable quality are taken, for the purposes of subsection (4), to have been specifically drawn to a consumer’s attention if those reasons were disclosed on a written notice that was displayed with the goods and that was transparent.
(6) Goods do not fail to be of acceptable quality if:
(a) the consumer to whom they are supplied causes them to become of unacceptable quality, or fails to take reasonable steps to prevent them from becoming of unacceptable quality; and
(b) they are damaged by abnormal use.
(7) Goods do not fail to be of acceptable quality if:
(a) the consumer acquiring the goods examines them before the consumer agrees to the supply of the goods; and
(b) the examination ought reasonably to have revealed that the goods were not of acceptable quality.