Originally Posted by Chief
it shouldn't be your banking password, it's your credit card verification password, and it's done through your bank's website not theirs.
^ This - known as "Verified by Visa" or a Mastercard equivalent generally.
NAB's - Credit Card Security - Verified by Visa - NAB
ANZ's - Verified by Visa | ANZ
Other banks will have similar info on their websites.
That said, I've never been able to successfully signup to the Verified by Visa run by my Bank. I continually get the run around with the suppliers (plural) blaming the bank and the bank blaming the suppliers. Given it's supposed to be secure communication with the bank I can't quite see on what grounds the bank can blame the supplier for even registering for the system not working. Usually I have the option at time of purchase to "Register Later" but after 3-4 goes of doing this it forces me to register, which of course fails. I've found though if I phone the bank's help line they'll reset the count and a couple of hours later I'm good for another 3-4 purchases.
Probably a conspiracy between my wife and my bank manager trying to get me to spend less on game sales.