What can we carry on the airlines in South Africa???

We are noticing that there is some confusion over carry-on baggage limitations on our flights between locations within South Africa...the airline's web site says one thing, their customer service personnel (by phone) another. I guess we'll just go prepared for the worst case scenario! Also, one section of our flight is on British Airways, between Johannesburg and Victoria Falls, and that route is subcontracted to Comair! So we are flying out of Cincinnati to Africa, then taking a Cincinnati-based airline once there. Go figure.