i'm going through something similar... the bottom 3/4 of of my hair makes awkward, limp,stringy waves because i flat-ironed the hell out of it, but the top 1/4 is as curly as ever (3b). it looks bizarre. i've been experimenting with rollersets and my hair either doesnt hold the curl at all or becomes a ridiculous puffy mess. a curling iron is the only way my hair ends up looking decent, but heat styling was how i got myself into this mess in the first place, so... its frustrating. i'm going to keep experimenting and i PROMISE i will report back if anything works!