give it time
If you are headed for South Africa, getting there is a major part of the experience.
PLEASE give it the time to go to the south of Libya - it is EXCEPTIONAL, and will be one of the highlights of the entire trip. Every time I hear of people going straight across the top I can't believe what they're missing. If it's a cash thing, delay departure by a month and work day and night to earn the difference - it's worth it!
Er, rant over! For your local operator, go with Fessano, you'll have absolutely no problems.