Same happend with me, i am now waiting 3 weeks and still no stock to replace my broken iPhone 4 even well they scratched the thing when it was in for the "No Service" problem, so i sended it back and now waiting for a replacement..
Phoned them this afternoon... I was informed they have stock and it should have been shipped out at the end of the day. SERIOUSLY hope it gets here tomorrow.
Been waiting since the beginning of the month for them to wake up...
I've also taken this poor service by Vodacom up with Apple in the US... Let's hope it helps a little for others.
Vodacom is certainly not living up to the quality & service Apple is known for in the rest of the world