Providing a discount on the card bin in Internet acquiring?

Question

Payment systems

Good afternoon!
There is one site and Internet acquiring is installed.
There is an idea to automatically provide a discount when paying with a card of a certain bank through the Internet bank.
You can determine the bank automatically by the card bin (the first six digits of the card number). The difficulty is that the client enters the card number on the bank's website.
How can this be implemented?

Answer 1

The acquirer gives you the card number (where some numbers are hidden, but BIN is just there). After payment, you can credit this discount to your internal account and allow it to be used for next purchases or implement some scheme with adjusting the amount of payment from the acquirer.

Answer 2

This is physically impossible because it violates the rules of operation (anonymity for all, except for payment systems) cards.