i had the same problem, my hair was chronically dry, tried a huge range of shampoo, conditioner, products, masks, you name it, i paid big $$ for it, all to no avail.

i started to supplement my diet with EFA's and switched to ...gasp...
pure soap to wash my hair and WOW... it feels awesome now, not more dry or split ends, easy to manage and it is just scrumptious now.
my hairdresser, who knew of my plight, was gobsmacked

i know heaps of people who do the same (which is how i learnt about it), some rinse their hair with vinegar water (1 Tbsp to one litre) because the water in their area is so hard, or just use rainwater.

not only is my hair soft now, but i am also laughing all the way to the bank, a bar of pure soap costs 50c and lasts for a month.
worth a try?