Here you can find a list of servers currently hosted in South Africa for Left 4 Dead:

VGS Left4Dead Versus Server:
196.207.47.111:21000
iGame Undead:
196.2.97.219:27016
-= SGS LEFT 4 DEAD VERSUS I Server =-
196.4.79.65:27017
VGS Left4Dead Server 1
196.207.47.114:21000
Server "/WAGE\ L4D coop
41.185.60.27:27015
-= SGS LEFT 4 DEAD II Server =-
196.4.79.65:27016
-= SGS LEFT 4 DEAD I Server =-
196.4.79.65:27015

Add them to your favourite server tracker (eg: Gametracker, HLSW, Xfire) and lets get the good times rolling!