Piet Retief - Pongola is really the only route... lots of roadworks but just be patient. From Pongola, it's Jozini turnoff, over the Jozini Dam wall and then follow the signs towards the Moz border. The road after Jozini da wall gets progressively worse... major potholes... you need to take it real slow here.
Give Deon Brits a shout - he stays in Piet Retief. Last time we went through there he showed us a few short cuts and we managed to avoid a few of the roadblocks. I'm not sure that this still possible though. Best to give him shout.