private function call($module, $params = array()) {
    // set api data
    $params['api_key'] = $this->api_key;
    $params['format']  = $this->resp_type;

    // build URL
    $url = $this->endpoint . $module . '?' . http_build_query($params);

    // Set URL 
    curl_setopt($this->ch, CURLOPT_URL, $url);

    // Send the request & save response to $resp
    $resp['data'] = curl_exec($this->ch);
    if (curl_errno($this->ch)) {
      throw new GiantBombException('API call failed: ' . curl_error($this->ch));
    }

    // save http response code
    $resp['httpCode'] = curl_getinfo($this->ch, CURLINFO_HTTP_CODE);

    if (!$resp || !$resp['data']) {
      throw new GiantBombException("Couldn't get information from API");
    }

    return $resp;
  }