ga-refund.php

<?php

var_dump(gaSendRefund('2642236223'));

function gaSendRefund($transaction_id)
{
    $url = 'https://www.google-analytics.com/collect';
    $tid = 'UA-XXXXXXX-X';
    $params = http_build_query(
        array(
            'v' => '1',
            'tid' => $tid,
            'cid' => sprintf(
                '%04x%04x-%04x-%04x-%04x-%04x%04x%04x',
                mt_rand(0, 0xffff),
                mt_rand(0, 0xffff),
                mt_rand(0, 0xffff),
                mt_rand(0, 0x0fff) | 0x4000,
                mt_rand(0, 0x3fff) | 0x8000,
                mt_rand(0, 0xffff),
                mt_rand(0, 0xffff),
                mt_rand(0, 0xffff)
            ),
            't' => 'event',
            'ec' => 'Ecommerce',
            'ea' => 'Refund',
            'ni' => 1,
            'ti' => $transaction_id,
            'pa' => 'refund'
        )
    );
    if (false && function_exists('curl_init')) {
        $ch = curl_init($url);
        curl_setopt($ch, CURLOPT_POST, 1);
        curl_setopt($ch, CURLOPT_RETURNTRANSFER, true);
        curl_setopt($ch, CURLOPT_POSTFIELDS, $params);
        return curl_exec($ch);
    } elseif (ini_get('allow_url_fopen')) {
        $opts = array(
            'http' =>
                array(
                    'method' => 'POST',
                    'header'  => 'Content-type: application/x-www-form-urlencoded',
                    'content' => $params
                )
        );
        $context = stream_context_create($opts);
        return file_get_contents($url, false, $context); // POST
//        return file_get_contents($url.'?'.$params); // GET
    } else {
        return false;
    }
}