Non delivery of E-Natis document.

I bought a used bakkie which I settled in January 2015 and I was promised that the Natis documents would be sent to me. I have not received the said documents to this day. I have made several attempts both by email & telephone to no avail. The only response I get is that the document will be sent. This is causing serious strife as I want to sell the vehicle but cannot do so without the natis documents.