Not sure I agree.
On the homepage you see clearly two relevant statements at the top of the page:
"Free Freight on dozen lots to 98% of Australians"
And:
"FREE SHIPPING
AVAILABLE*"
Clearly an asterisk indicating further details of the terms are available.
Following that link you get:
"Non Dozen Surcharge
The following surcharges apply:
Non-dozen Lots - $10 surcharge
or
Fewer than 6 bottles total - $20 surcharge
(Buy in 12 bottle multiples, straight or mixed to avoid these)"
For me when you state '
surcharge' it seems clear.