So this happened to me recently.
I paid for an accomodation on Airbnb in SGD on the website. However, when I received my credit card statement, I saw that the amount charged in SGD s higher than the receipt. I checked with Airbnb customer service and they said that this cross border fee is levied by the bank. I called the bank and they said its levied by Visa. The amount was ~S$7.
Does anyone here know how do I get this back?