$orderXML = new SimpleXMLElement($orderXMLString);
 
$orderXML->OrderNum = 'MyUnicumOrderNumber-1234567890';
 
$orderXML->PartNum = 'T5D-00432';
 
$orderXML->quantity = 1;
 
$postString = $orderXML->asXML();
 
$returnOrder = do_https("https://sandbox.webstore.mont.ru/B2BService.svc/web/AddOrder", $postString);