Caprivi Strip - need to google some outfits there and I am not sure when is the best time. Need to take your own tackle most places.
Vic falls, Zambia side - many operators there who will take you out. Can be a bit pricey but all is negotiable. Some provide fishing tackle.
Kariba also has a few nice fishing charters, caught my PB there.
Google is your friend....you will find the operators, just do more searches to see if they are reputable.
Cheers