If cocoa farmers want to increase the productivity and quality of their farms, this usually means they have to invest in their farm, both in terms of time and money. Not many banks give loans to smallholder farmers; they tend to see farmers as unbankable and tend to avoid the high transaction costs in bringing financial services to rural areas.
Increasingly, other institutions and companies become involved in financial service delivery to organized groups of farmers, e.g. they provide inputs on credits. There is still a lot to learn about what type of finance works for what type of farmer, and how the risks involved (both for the farmers and for the service provider) can be mitigated.