from recollection, during the GFC banks stopped lending to each other and were pulling debts back in (hence the credit crunch). Because of this Bank West was not able to get funding and their parent company (i think the bank of Scotland?) was wiring them billions every month to cover the gap. But after a while was not able to keep supplying them money so made the bank go bankrupt.
I believe the RBA bailed them out for a few weeks, and then CBA took it over and then funded it.
Actually good news! there was a documentary on 4 corners a few years back and looks like they have the episode on their website. Pretty sure this explains what happened and how it affected bank west business customers.
