I too use a travel agent for trips to Africa, mostly for the reason you mention.
So many people say they book on their own, and don't see the need for a travel agent. I can identify at least three ways in which they are invaluable:
1. I've found that for some reason, they can often get better prices than I can. It may be easier for some who can take one airline all the way, but I have to take at least two major airlines, and invariably, my travel agent can find a fare that is better than I can do. Often, the difference is material.
2. If something goes wrong, you have someone you can call 24 hours a day who can likely be on the phone more than you can.
3. If you need to change your ticket, such as when you finish a hunt early, it's a heck of a lot easier for a travel agent to do that than it is for me. This depends of course on where I am in Africa, but in some of the more out-of-the-way places, you could spend a lot of time on the phone, if you can even get a phone. Most recently, in Ethiopia, I wouldn't have been able to change my own tickets given the communication issues, some (maybe all) of which were caused by the state of emergency there. A text to the travel agent and she sorted everything out.
Frankly, travel agents charge so little for their services I wonder that they stay in business. Worth every penny.
PS. I'm not a travel agent and I'm not related to any!
