I need help adding a processing fee that is based on the credit card my customers use. For example, if they have a VISA card or MasterCard, I'd like to charge 3%. Also if they have an American Express card, then I'd like to charge 5%.
I can't seem to find a plugin that can do this nor do I know any code to write this. This is in the same payment gateway, not two seperate ones.
What can I do and is this possible?