Qantas is a dreadful airline with terrible customer service
Qantas is a very unreliable airline with terrible customer service, but high costs.
They change their airline times to suit themselves and with little notice. They don't care about their customers at all.
They use Cookies wasting hours of customers' time. As an example, you book an international fare to Australia. You want to link it to a domestic fare and then the domestic airfare price - which you have checked well beforehand - suddenly goes up within 3 minutes of doing the international booking. It is impossible without Cookies.
Winning Lotto has more likelihood than this happening.
Use any other airline, but don't use Qantas unless you have no choice at all. They are very dishonest.