Originally Posted by corporate-wage-slave

One of my tetchy annoyances is that many on FT - and I'm certainly not just getting at the OP - can be a little non specific in their posts. But in this case the OP has subsequently indicated they would ideally like an extra night in Australia so that they can leave on Saturday instead. Now it is best to be clear about that first, since if s/he wanted advice on that then it would be forthcoming:
- if you definitely want to do this, ring up and pay up, it probably won't be cheap, perhaps several hundred dollars.
- if you don't want to spend that some of money and you may be doing the same trip within 355 days of the original start date, then consider rebooking to the cheapest date in the future. If it is the return leg this may not be too prohibitive, though again it depends on the circumstance. Then find a Saturday travel arrangement which is cheaper than BA.
- if you're ok to take a punt that the flight is in fact overbooked, then look at the time of check-in opening in MMB, go to the airport at an early part of the check-in process and ask if they are looking for volunteers to go the next day. It's not totally clear which cabin the OP is travelling in, but if in CW I would say the chance of that is 20% or less.
- If on a redemption, various other factors apply.