What if there is a delay between receiving the bitcoin to doing the payment, for example if the payment gateway is down? Would that imply custodial or depository service?

Definition of "custodial or depository service": http://www.austlii.edu.au/au/legis/cth/consol_act/ca2001172/...

There's nothing remotely similar. The Bitcoin payment is not an arrangement nor a financial product. It's not held in trust either.

Thanks for the link. I wouldn't want to rely on my interpretation of reading that Act to keep myself out of trouble! There are so many links that go to fairly unhelpful definitions such as 'when used in a provision outside Chapter 7, has the same meaning as it has in Chapter 7.' So it's not a settlement facility etc, it seems exepmt from these if it's not considered a financial product?

Out of interest, do you know what a similar service that accepted AUD instead would be classified under?

and then the only person who can do a charge-back if required is you...