When I was still residing down in Durban(about 5 years ago), we use to troll + 6inch soft plastics and hard plastics across the North to South pier channel, yes I use to row across the channel with my fishing ski.
We used to catch lotsa Pick handle barracudas, garrick, kingfish,wala wala, springer. It all depends on the depth of your lures and also the speed that you troll!(most fish prefer faster trolling)!!
Another good area used to be the channel from wilson wharf across to the centre bank! Have you tried trolling a whole sardine or squid? They also work!!
All the best Mr. Zippo and keep us informed Dude