i have shoulder length wavy hair..many years back i tried thermal reconditioning or what u call chemical straightening and was very happy with the results..and i repeated that twice intervals of two years..neways now i use only a solia hair iron(which is just awesome-better than the CHI) but my doesnt remain straight for longer durations(abt 4 days before i have to retouch my hair with the iron)...infact my hair starts becoming wavy withing 3 hours!!!
i have also tried all kinda anti frizz,heat protectant solutions/sprays/straightening balms but to no avail..please help!!!!

maybe you should go back to the chemical straightening? but i can see how that can get really expensive. maybe try like a thick straightening balm before you straighten, then put something else in after also. i had this really thick straightening balm, but my hair is already pretty straight, so it was TOO thick for me. i ended up giving it to my friend because she has wavy hair and it works really good on her.

I have never been able to keep my hair straight longer than a day by straightening it with a flat iron, but what I do is put some of the avon straightening stuff on when my hair is wet then blow dry it straight with a paddle brush flip my hair over to do so and then I CHI it and it stays all day but not after I go to bed I HAVE to wash my hair everyday anyways so you know!!