Could this not be "ongea kaka"?
Yes, it could definitely be that. In some regions, "sema" is used for "speak" but elsewhere it is only "say" and speak would be "ongea" (and in some areas, "zungumza" would be preferred).
It definitely could be. Sema tend to lean towards meaning 'say' whereas ongea is a better word for speak or talk.