In the checkout before you complete your order there is indeed a comments box, its very well positioned and hard to miss.
We used tracked mail because without it, its impossible to know if items have gone missing legitimately or if someone is having us on unfortunately, I am by no means saying this was the case, just giving an explanation.
When paying for tracking this does give you a guarantee on your order so long as tracking is available for your location.
We have next to zero issues with Australia though so without knowing details of your issue I cant comment too much but please also remember sometimes orders get delayed at customs. For example I just had a regular customer who won a prize in one of our competitions but did not receive his parcel to India within 3 weeks so I sent another (even though we don't guarantee competition prizes) and BOTH parcels arrived within days of each other.
However, if your order was nabbed at customs then we will guarantee that and resend for free buddy!
Can you contact me directly with your order number or name on your order so I can investigate further for you.
Email me direct at firstname.lastname@example.org