Every bank account I have requires two factor authentication to set up a new destination for your money, so if you have fingerprint authentication on your phone don't let them steal your phone and your finger
This is a completely routine thing, that information is required for any electronic transfers to take place.
In theory they can use it to drain your money by initiating a transfer the same as if you were transferring money, but if an improper transfer were done your bank would reverse it if you tell them soon enough.
That sounds like a real pain. If I were in your shoes, I would try contacting the relevant regulatory body/consumer protection agency, which in this case, I believe, are one and the same: https://www.centralbank.ie/consumer-hub/explainers/how-do-i-complain-about-a-financial-services-firm
Although I'm not sure how much attention you're going to receive ...