Not really whoknows...I've always had the same problem with everything other than GHDs - but GHD's stays well in my hair.
OP, if you can't master a relatively quick and reliable method that stays well and only takes about 10 minutes, much as this sounds trite, its probably just best to try and find a style that works with the natural texture of your hair. Otherwise you are just always fighting it and forking out £££ on fighting it.
Sure, try the perm but it is £££ and perms are not without their problems - particularly when they start to grow out. Back in the 80's when I had a perm (and of course they have changed a lot since then) I had trouble with one section at the front of my hair being straighter than others and it dropped quicker than the rest so I had to curl that to make it match (if only they had GHD's in those days)! and I do wonder if the digi perm would drop out quite quick.
So its not much help but is there some way you can find a cut or style that is what works with YOUR hair and just learn to love that for everyday...then you can save GHD's or tongs or that wavy thing for night's out...this may be well what you are doing already and fancy a change, so I'm probably talking crap but I've known people who have fought their curls for years just embracing it and going with it and they are glad in the end that they have just found something that works with their natural hair - its liberating. Well, this is kind of the opposite really...
I do the GHD's thing because I feel my hair should be several inches shorter and blow dried if I'm going to have long hair at my age without looking schoolgirly, but it takes so little time and its only twice a week, that just works fine for now but one day I probably will find the right choppy bob or something. And I am not pushed for time...but if you are...