public function cancelHeldAuth(CardPayments\Authorization $auth)
    {
        $auth->setRequiredFields(array('id'));
        $auth->checkRequiredFields();

        $tmpAuth = new CardPayments\Authorization(array(
             'status' => 'CANCELLED'
        ));
        $request = new Request(array(
             'method' => Request::PUT,
             'uri' => $this->prepareURI("/auths/" . $auth->id),
             'body' => $tmpAuth
        ));
        $response = $this->client->processRequest($request);

        return new CardPayments\Authorization($response);
    }