protected function _convertAdditionalData()
    {
        $details = @unserialize($this->getInfo()->getAdditionalData());

        if (is_array($details)) {
            $this->_billerCode = isset($details['biller_code']) ? (string) $details['biller_code'] : '';
            $this->_ref = isset($details['ref']) ? (string) $details['ref'] : '';
        } else {
            $this->_billerCode = '';
            $this->_ref = '';
        }

        return $this;
    }