We're driving ourselves with a Toyota Landcruiser to South-Africa and we had some problems in Nairobi.
You can get help in Jungle junction but they told us that it was quite expensive.
If you're able to repair it yourself you can buy spare parts at' Cmmercial Motor Spares'. They are at 13 Dungard/10 Bandari Rd and they sell real parts, no fakes. email@example.com
I saw that they also had a garage, but we didn't have it serviced there.
We had it serviced by a local, that another traveller recommended and we are happy about the service. The person in charge is Joe, he used to work in the UK so his English is very good. firstname.lastname@example.org
(if you go there, please say hi from us!)
We never paid more than 1500ksh per hour.
At the moment we're updating our site with this usefull information, keep an eye on it if you need something later
Eef and Dries