Firstly avoid Yobit.net, a number of us have lost out due to withdrawals being disabled they were given ample opportunity and time to sort the wallet out, do not chase cheaper prices and apparent arbitrages, it will bite you in the ass.

Saying that, Cryptopia are a top exchange with increasing volume for alt coins all the time.Unfortunately some trading pairs like kobo/litecoin and kobo/doge had to be disabled along with all the others because they were slowing the exchange down too much, so its only bitcoin and tether pairs, but interestingly they have the New Zealand tether dollar (they introduced it, btw)

Coinexchange.io are fine AFAIK, but volume is small for kobo.
Those are the 2 options until an African exchange such as Cryptoafrica introduce a direct fiat to kobo system, they have it on the main page but in the options Kobo is not yet enabled, is this coming soon, anybody know about this?

Good luck