Bad after sales service,

I have bought a second hand vehicle in November 2014, I only received an invoice about a month later after I had to go and beg them for one. The staff could not even find the file of the transaction. Eventually I got an invoice, but still no Natis papers for the vehicle. They never return calls and never have any feedback on what is going on with the Natis papers. I have contacted the head office but due to the vehicle being second hand they can not do much. The vehicle has to go through road worthy again and the license is almost expired. How long will this still take really.? When you phone no one knows what is going on and they always have excuses.