Discovery will not pay for much needed testing

I suffer from low blood pressure and its being getting worse over the past 2 months my Dr had referred me to a Physician and it was declined by discovery. The reasoning was that its not clinically appropriate. I pay every month for my medical aid. And its a serious condition yet these amazing ******* want to decline everything. I cannot even get out of bed on certain days. Why should i pay for this when i have a specialist benefit. The reason for my low pressure needs to be ruled out!!! Frustrated with discovery and the unrealistic rules.