NWASimon - If you can't get through by phone it might be easier for you to go to the KL center in downtown Nairobi. I had a mix-up with one of my tickets (they somehow gave up my seat) when I was there two years ago and had to grap a matatu from Nakuru to speak to someone. It was a pain, but actually being able to explain my situation in person really helped, plus I was able to get an exit seat. Hope that helps.