Medshield waiting period story

Medshield waiting periods....... My kids are 4 and 7, were both diagnosed with sinusitisis since their first year of birth ( 3yrs and 6yrs back), and hv since been on treatment. Recently we moved them from discovery to medshield and they imposed a 12 months waiting period. they hv never spend a day long without a medical aid. I can not take them to any doctor for any medical condition. is this a ****??! at some point they were on medshield before joining discovery,treated for the same condition and now they just can not receive treatment anymore. Discovery hv never imposed their waiting period stories, why with medshield?? this isn't a new medical condition..... and if so why not be treated for any condition??!!!