public function download()
    {
        $oUtils = \OxidEsales\Eshop\Core\Registry::getUtils();
        $oUtils->setHeader("Pragma: public");
        $oUtils->setHeader("Cache-Control: must-revalidate, post-check=0, pre-check=0");
        $oUtils->setHeader("Expires: 0");
        $oUtils->setHeader("Content-Disposition: attachment; filename=vouchers.csv");
        $oUtils->setHeader("Content-Type: application/csv");
        $sFile = $this->_getExportFilePath();
        if (file_exists($sFile) && is_readable($sFile)) {
            readfile($sFile);
        }
        $oUtils->showMessageAndExit("");
    }