Add payment method title to Fortnox order-comments

functions.php

<?php
 /**
 * @snippet       WooCommerce - Fortnox plugin by Redlight Media - Add payment method title to Fortnox order-comments via functions.php
 * @author        Redlight Media AB / Christopher Hedqvist
 * @compatible    WooCommerce 3.2.6
 */
function redlight_fortnox_payment_method_title( $orderData, $order_id) {
    $order = wc_get_order($order_id);
    $orderData['Order']['Remarks'] .= "\r\n"."Betalsätt: ".$order->get_payment_method_title();

    return $orderData;
}
add_filter('obj_fortnox_order_data', 'redlight_fortnox_payment_method_title', 10, 2 );