No cooling off at auction. No finance clause, no special conditions.
Auction conditions apply even to negotiated sale 3 clear business days prior to or after date of the auction, or the advertised date if the sale occurred in the 3 days prior.
If you can't get the agents bank details, try harder. I doubt they'll call it all off if you're a day late, but you could technically be in breach of contract. Consider showing up at their office with a bank cheque.