Finally heard back from Eastern European hotel.
Please kindly be informed that I have investigated the situation and the exchange difference in question has happened due to a system error as the GIVEX system has redeemed the amount incorrectly because of discrepancy in foreign currency exchanges.
I have now proceeded with correcting your invoice and sending the refund case to our Accounting department, who will then shortly refund the amount of xxxx to your AMEX credit card ending on 8490.
Actually the currency exchange was added to my folio, not by a system error by Givex, but whatever. And I don’t have a credit card ending in 8490, so we’ll have to sort that out.
But I am happy with the outcome and hopefully it won’t happen again.