Firstly, it would be interesting to know if you have discussed alternative medications to control you medication, seeing as there are other pharmaceutical classes available. Also, it is important to classify your hypertension level, what is your mean BP for example.
Also, be advised that all ''natural'' hypertension alternatives have evidence levels backing them close to nil. Going for ''natural'' compounds when you are experiencing severe hypertension would be ill advised. If you were suffering from mild hypertension then it could be considered. ( Seeing as you are on both a diuretic and a calcium-channel blocker, I am not confident that switching would be the wisest decision)
Things that might have an effect as reported by one or two studies per agent:
Weightloss (Known to work)
Low-dose aspirin taken before bed
Low-sodium diet (works if you are a responder)
200 IU Vit. E/day
A low daily dietary supplement of K, equivalent to the content of five portions of fresh fruits and vegetables
Many possible herbs/spices are being investigated, most of them have anecdotal or extremely limited evidence behind them.
Be careful, and discuss this with your physician. Trusting these forums and ''naturopaths'' can be dangerous, especially for high-risk pathologies like hypertension.