Watered down chronic benefit through the years

I am a member of Discovery Health for more than 20 years and the so called chronic benefit have been watered down trough the years. They initially paid full for the original medicine. Then, they changed it to pay full for the generic medicine and now only a small portion of the cheapest generic medicine with the following as the reason "We have paid up to the monthly Chronic Drug Amount for this medicine class. You need to pay any claims above the Chronic Drug Amount for the remainder of this month." They currently only pays R45 out of about R135 for my monthly chronic medicine.