Writing from Istanbul Turkey...Our shopify system is set to EURO and we are using a payment system called IYZICO.
Customers can not pay with Amex card. IYZICO says Amex makes payments only in local currency; that is why Amex payments rejected.
Shopify tells me to go Iyzico and Iyzico tells me to go Shopify to fix it. Insane! Losing a lot of business !
Any advise to fix this problem?