@jetway It doesn't work like this unfortunately. Let me explain that with an example. Let's say I have a 'NoCreditCard' customer group in my shop for customers that I don't want to to pay with credit cards. Yet these customers belong also to the default 'Customer' group. And what I want to achieve is to make credit card payment available for all customers besides these that belong to 'NoCreditCard' group. If I make credit card payment unavailable for 'NoCreditCard' group in payment preferences, customers that belong to this group still get this payment option because they also belong to the default 'Customer' group (and I don't want to kick them out of the default group because then many features stop working as they should).
I'd be grateful for a suggestion where in the code should I apply a rule like: if a customer belongs to XXX group >>> do not show YYY payment method