So far what everyone else said is right on. You're already using salon products, but sometimes if it's the wrong type of salon product it won't help, so I would talk to a hair dresser just to make sure. Pureology makes some amazing shampoo, but I know that I used the wrong one for a while and that's what happened to my hair. I now have the stuff in the gold bottle and that helped a lot.
Also what I do is I try to never blow dry my hair, I know it can be annoying and sometimes hard to get used to, but I'll actually wash my hair at night and let it air dry (or if I know I'm not leaving my house for a few hours I'll let it air dry in the mornings before straightening). This has actually made a big difference for me personally. Also like it was mentioned, try to give your hair a break every now and then - even if it's just keeping it straight and not washing it for 2-3 days, it allows the natural oils to heal your hair, but if you can have it curly then I would try that. I use the Catwalk Tigi Curls cream and I love it (my hair is VERY curly).
And a good heat protectant. I know that Redkin has a really good one that's a sort of oil. It's in a brown bottle and it lasts forever. I use it before straightening and also right after to smooth away any flyaways - plus it smells good. Also for smoothing down frizzies, if you like Pureology then you can use the Dryshine Styler goup (I think that's the name...) but it's in a yellow container with a purple lid and you only need a tiny bit and it works great. Also good for holding bangs back if you pull them straight back or do a severe side part.
Hope this was helpful. Good luck!