The Recipient is Unknown ?

I have ordered a book from Berlin, Germany. The delivery address is my workplace in Holborn, London. The status of my shipment is 'Recipient is unknown' and it says that DHL attempted delivery last Friday however my workplace was unaware of any attempt. <br> <br> I would be grateful if the relevant supplier would contact me and check the status of this shipment. <br> <br> Thanks<br> Nikki