refusal to pay back my money

Have had this policy with clientele life for 10 years and cancelled it yesterday and they refused to pay me back the cash back. They said if you don't use the policy after 5 years they give you a cash back, I have been with them for 10 years and no cash back. I think it is a bit unfair if you spend 800 rand a month on a hospital plan and they don't pay you anything back, it is a lot of money you lose at the end.