Was under the impression that we can set the interface with NAB Transact to send all transactions to "Preauthorisation" status type, as opposed to automatically making the payment. This is to reserve funds for later completion of the transaction.
The underlying "NAB Transact" Moto system, available on computers and tablets allows the choice of either "Payment" or "Preauthorisation".

Having spoken to NAB, they say the preauthorisation capability/option should be available on NAB Transact eCommerce via the Plug-In. As it stands now, we cannot see that this setting is available.