I modified the line:
echo $this->vendor->vendor_name .'<br />'.$this->vendor->vendor_phone .' '.$this->vendor->vendor_store_name .'<br /> '.$this->vendor->vendor_store_desc.'<br />';
by removing ".$this->vendor->vendor_phone .' '.$this->vendor->vendor_store_name .'<br /> " .
but after that, the invoice did not get mailed either to vendor or the buyer.
even the page that is generated after the checkout, does not show up.