Changing layover dates for an Australian transit visa [closed]

I am an Indian citizen. I booked flights from Chennai, India to Port Vila, Vanuatu via Brisbane, Australia on August 13, 2018 with a layover in Brisbane, Australia on August 15, 2018.

I have applied for an Australian transit visa, stating that I will be in Brisbane, Australia during the layover on August 15, 2018. Unfortunately the visa did not come through in time.

I had to reschedule my flight leaving it as an open ticket. I intend to buy a ticket after the visa has been processed.

Can I use the same transit visa for a layover at another date? If not, can I request for a change of date on the transit visa? Is there a way I can keep it an open date by requesting the Australian embassy?