There is a Jetstar Kids Fly Free Sale to Bali ending at 10 pm AEST, 22 February 2016.
The offer applies to flight and hotel packages at certain hotels. There has to be 2 adults traveling and the kids have to be between the ages of 2 to 11.
See: http://www.jetstar.com/au/en/special-offers/kids-fly-free-to-bali#/?from=adelaide&to=&date=&sale=&price=