public function createTransaction($order, $amount, $transactionType = '0')
 {
     $Sermepa = new Sermepa($this);
     $this->Controller->request->params['sermepaUrl'] = $Sermepa->getPostUrl();
     $this->Controller->request->params['sermepaData'] = $Sermepa->getPostData($order, $amount, $transactionType);
 }