Ndiddy,
If you stay on the same level of cover or similar there is no waiting time to serve for an existing medical condition.
An upgrade waiting time of 2 years only applies if you upgrade cover at renewal time, to include extra cover not on your previous plan.
Even then, the waiting time only applies to the existing illness/condition in respect of the extra cover on the new plan. Your pre-existing illness would still be covered as per the cover on the old plan while waiting. If you switch to a higher level plan, you never lose cover.
All new illnesses/conditions arising after renewal date are fully covered, including the extra level of cover on the new plan.
For a person taking out health insurance for the first time, with a pre-existing illness, the waiting time is 5 years in respect of the existing illness.
All new illnesses/conditions are covered after the initial 6 months are over.
So, the 2 year upgrade waiting time only kicks in after a person with a pre-existing illness has been on health insurance for a total of 5 years.