The renal arteries carry blood to the kidneys from abdominal aorta and the blood is filtered by the kidneys.
If the renal arteries are narrowed or clogged by arteriosclerosis, the kidney can’t get blood so the kidneys secrete renin which is a kind of enzyme to increase the blood pressure. But since there is a blockage in the renal arteries, the kidney still can’t get blood so again they secrete renin. This process is repeated, resulting in the high blood pressure.
If your blood pressure doesn’t go down with the medication you take now, there is a possibility of the arteriosclerosis of the renal arteries.
In that case, you need to change the medication to the one which weakens the function of the hormone affected by renin and/or widen the narrowed renal artery by a stent that is an expandable tube.