According to Sweet Memories:
Cabana - Cadbury concoction of the sick-making variety. Coconut, caramel and whole cherries encased in milk chocolate - oorgh, no more for me, thanks. Lasted for about a year in the early '80s. Ads, as with Trio, featured the Banana Boat Song, replacing "Day-o!" with "Cabaaaa-na!" to little marketing effect.
But they also reckon Fry's Five Centres was called the Rainbow Bar, so posibly unreliable.
The Chocolate Project lists Cadbury, Nestle AND Rowntree as the makers!