Discovery life will take premiums for two years then void policy when you have a claim

Discovery life takes premiums but when it's time to pay on a claim they say pre existing symptoms and void the policy after receiving premiums for nearly two years.So basically they don't pay and clients like myself suffering from dreaded diease is left without no cover for dreaded diease,disability and income protection because they void the policy when it's time to pay and when an individual has a dreaded diease like lupus and on chemotherapy no insurance will cover me now so no help for me or my family.