Yes, it can be handled online. Actually, Chase used to (or still might) have something about "if this is about the billed currency, choose this option". I think that would show up if you had selected that you were overcharged/charged an incorrect amount. I would say, "I am requesting a Reason Code 76 chargeback to be billed for the transaction in local currency. The merchant refused to honor my currency selection at the time of purchase, and I was not offered a choice."