@Wilhelm *********
That's unfortunate.
I don't think that the airline would change it without you initiating the change, although they may make a fuss about it, in which case you could point out that you can extend your visa for 30 days in country (if you're on an Australian passport). Although, if they offered a free or cheap change, I would take it.
You shouldn't have to pay a fine for 1 day overstay but you will get a note in your passport... as long as you don't get caught before getting to the airport. Get caught and it's another world.
If your flight out on the 17th is in the early hours of the morning e.g. 1am or 2am, etc you could go through immigration a little early on the 16th to avoid being on overstay.