FOX - WooCommerce Currency Switcher Professional

Plugin URL: https://woocommerce.com/products/payment-gateway-based-fees/

//In file \plugins\woocommerce-additional-fees-2\classes\class-wc-add-fees.php  function  calculate_fees add next code
if (class_exists('WOOCS')) {
    global $WOOCS;
    if ($WOOCS->is_multiple_allowed) {
        $add_fee_fixed = $WOOCS->woocs_exchange_value(floatval($add_fee_fixed));
    }
}

//AND  add this code
if (class_exists('WOOCS')) {
    global $WOOCS;
    if ($WOOCS->is_multiple_allowed) {
        $add_fee = $WOOCS->woocs_exchange_value(floatval($add_fee));
    }
}

//AND  in function &calculate_gateway_fee_total add next code
if (class_exists('WOOCS')) {
    global $WOOCS;
    if ($WOOCS->is_multiple_allowed) {
        $maxval = $WOOCS->woocs_exchange_value(floatval($maxval));
    }
}