Firstly you need to take care of yourself.
If they are refusing to pay you and you are coming here to make an "anonymous public statement", it is fair to assume that your employer didn't like what they heard or quite simply how they were told.
It is important to remain true to your values, raising it with your employer and explain why you are uncomfortable with that would have been my number one suggestion. She/he should be able to understand. It looks like she/he did not, my suggestion would be to raise it to she/he managers and managers manager. Always calmly and respectfully, as most likely there isn't necessarily a malicious intent.
Secondly, if you are really keen to reach out to the bank I'm happy to do it for you as I know quite a few security teams in the major banks. But please do not disclose who you are. Email me at 6lh008+1lhx68glu7jh83h8r9pxo7ad9wc8uao@pokemail.net