I highly doubt ZF would do a conversion.
My mechanics are Brilliant Mechanical Workshop they are in the southern suburbs next to kenilworth centre. Here is their webiste not too flashy but anyway:
http://www.m1group.co.za/Workshop.html
If you are in Northern Suburbs your best bet is garage 808 as its closer. I cant speak from personal experience with them but a lot of forum members recommend them.
You are more than welcome to come check them out and come for a spin in my smokey diesels, well only my 320d is smokes. The 330d had to quit for health reasons as he's getting old (sorry bad joke). Or check come to the next meet which I will hopefully be attending as I've been away so I missed the recent trip to Hermanus.