Same Priority for Credit Cards and Bank Accounts at the customer site

Hi,

So my question is , if a customer has both a credit card and bank account assigned at it site, and they both have priority 1, what payment instrument would be picked up at the time when we are billing the customer. 

I should add that the receipt method attached to the customer is a user defined manual method called CC VISA and we are not using the seeded Credit Card automatic payment method.

Thanks,

Aditya