I use a hair straightener! I only use a cheap-ish shampoo for normal hair atm, as my hair has been a bit yuk from hormones.
A bit of hair moisturiser on the ends so the straightening doesn't dry it out, (i use schwartzkopf when I use it) and a spray of heat activated straightening stuff.. that smells suspiciously like vinegar.... (also schwartzkopf) and my hair looks and feels reeeeeeeally noice! no frizz, no waves, just dead straight swishy hair!

contemplates whipping out the straightener....

I have had a pretty shocking experience with Pantene - my hair started to actually break and fall out! Wasn't a good hair day (or few months) at ALL!! I still cringe at the memory.

ETA - Kim, I remember Flex! I remember it smelling kinda candy-like. Might look out for it next time I need to buy shampoo