Hi
I am sorry to have missed your first message: we were on tour.
As far as I could find out, there are no flights on the route you requested. You will have to fly via Johannesburg. I think you may be able to find a smallish ship to the north of madagascar, but I presume you dont have time for that.
As a last possibility try to phone interair in johannesburg. They are a big airline in southern Africa.
Good luck,    Martin