You simply have no choice. You either involve the banks and get permission or your app is dead in the water.
Quote:
they will not be happy with my app
Well, that tells me you're not going to get the permission from banks, even if you ask. So, again, you're app is probably dead in the water.
Granted, I have no idea what your app does, but if you're saying this, it can't be good for the bank and will probably just piss customers off too.