General, page-798

spot on Susieq.
The additional shares are subscribed for under the "Shortfall Offer".
They state that the maximum number of shares you can subscribe for under the Shortfall Offer, is double your original Entitlement.

So if you have 100,000 shares currently, your Entitlement is 40,000 new shares. You are ensured to get these. That costs you $2400
Then if you are still hungry, you can apply for a maximum of another 40,000 shares under the Shortfall Offer. That will cost you another $2400.

So using your Bpay reference, you can forward a payment of $4800 to registry.

If you are allocated less than the extra 40,000 shares under the Shortfall Offer, they return the difference of funds to the bank account detailed on your account at the registry.