When you specify a Auth it overrides clientID as under Kraken, the oauth key is used to look up the clientID for it.
However your PHP Code is wrong.
For cURL headers should be:
$headers = array(
'Authorization: Bearer '.$extension->getAuthentication(),
'Content-Type: application/json'
);
So the headers you are passing are completely wrong. (Note I omitted Client-ID here, but personally I leave it in all the time)
No need for the CLientID in the URL/query string, just fix your header sending
Revise: Make sure you have a
curl_setopt($ch, CURLOPT_PUT, true);
In there somewhere