Amazon (USA ordering/shipping) has a practice of "under promising and over delivering". They will say it will take a week for an item to be received but send it faster. Gives the illusion if being a "good company".

Your case however, is a bit different. If item is still in a warehouse, contact amazon. If you're ordering from the USA site, and you're in Austrailia, it may be taking some time to approve funds/currency conversions/etc.