Maybe none of us have any idea, but I can read an ICAO Filing Form that states Aircraft Identification and Type of Aircraft. So you're telling me this was filed as an Airbus instead of a Boeing and Australian ATC missed it, the crew missed it, the dispatch team missed it and the Indonesian ATC as well. I am sure if it was filed incorrectly "months ago", then was there no way the passengers could disembark upon landing in Bali?
I may have no idea, but I have operated into there many times. So if you have an idea, instead of taking a pot shot, how about you tell us how such an error could occur? The stage is yours!