Hmm.. when he has one for the plant I need info. on, I like this guys guides with tag:
The Pogostemon Helferi is a beautiful foreground plant for aquariums. Its unique look is due to the curled appearance and dark green shade of its leaves.
www.theaquariumguide.com
Far as your pogostemon helferi, how exactly is it dying and how long have you had it? Pretty plant by the way I had never seen it before. Is it browning/yellowing, shriveling, thin and scraggly, etc. (any detail helps). Also, what is your pH and water temperature? Do you use any fertilizers? Can you provide any lighting specs?
Sometimes new plants in a tank will go through a 'dying' period as they adapt, but does not necessarily mean they're done for.
From what A. Edmond (TAG, date unknown) writes in that article, it can be grown in substrate clumped together, or spread out for carpeting. For carpeting - it does best when it is all started together, and once it's adapted you can then seperate bits of it about a half inch apart to grow carpet (helps to move past the initial shock of changing tanks when it's together). It can also be grown on rocks and driftwood.
Co2 will help it grow faster but isn't necessary. If you have it in the substrate, root tabs will help it's roots and it will rely on nutrient rich substrate. If it is on driftwood/rocks, liquid fertilizer will do it more justice since a lot of it's nutrients will come from the water column. You could look into making your own micro and macro fertilizers, but you could look into these too: seachem flourish, seachem iron, seachem potassium (always do research into any product before use in your tank, some ppl can likely recommend better products, these are just things I've used before to help dying plants).
In low light it is likely to get taller (to get the light it wants) and not as bushy, in high light it won't be as tall and will be more bushy.
Due to the constant changing waters where it's from, sounds somewhat hardy and forgiving. Try to keep it in water 73°-86° F, and pH between 6-7.
Don't worry about the frustration. Seems likely you'll find a wide range of info. on it because it is forgiving - I had almost the same situation with my baby dwarf tears, and their thriving w/o co2 and lower lighting.
I do like that 1 guys articles I paraphrased though, least for plants I have that he has written about - havent had any irregular problems with his advice.