Originally Posted by
corporate-wage-slave
It's after an investigation / review of reports from crew and ground agents, so no, it's not automatic. I don't believe the banned person gets to give input here, but there again it probably doesn't matter, BA can fire customers if it wants. There is also a yellow card scheme open to flight crew.
Echo C-W-S comments adding BA can and does take appropriate actions as it sees relevant to the circumstances. Bans/sanctions are varied and wide.