Qantas has a little deal (https://www.qantas.com/au/en/manage-booking/same-day-no-mist…) whereby you can change flight details with no change fees if you ring up before midnight on the day you make a booking. It's intended for situations where you accidentally enter the wrong name or book the wrong day and discover your mistake after booking.
This was recently handy for a friend of mine so I thought I'd share it for those who may not be aware of it. Not sure if Virgin has a similar offering?
old news, son.
10ish years late lol