Really dry, frizzy hair - please help!

[nickEcave]

I've always had quite nice hair - very thick, slightly wavy but could be blow dried straight. I'm now more than 50% grey and have to use home dye every 3 weeks or so to keep on top of the grey and my hair is becoming really lifeless, dry and frizzy. I know that the dying probably doesn't help - but please don't suggest letting it go grey, I'm only 41 and my mum was really grey by this age and looked 15 years older than I do with brown hair. I can't afford to get it done at the hairdressers. I wash about 3 times a week with L'Oreal sulphate-free shampoo for dry/coloured hair (switched to sulphate-free 2 years ago after years of problems with ecxma on my hands and it cleared up overnight!) I use an argan oil conditioner and Frizz-Eeze before blow drying. My hair is now so dry and crispy and I don't know what to do with it! I using Castings home colourant - is there something gentler that will still cover a lot of grey?

I have a keratin blowdry done twice a year.

Removes all my frizz and I can blowdry once a week in about 15 mins then it lasts me.

Best investment ever.

Thanks for all the suggestions. I had an inch or so off at the hairdressers yesterday and its looking a bit better. The hairdresser used some Paul Mitchell products on it which seemed to smooth it without making it greasy (this has been the problem whenever I've used serums or oils like argan oil on it - the frizz goes but it looks lank and greasy). Unfortunately Paul Mitchell products cost a fortune (nearly £20 per product!) so I will try some of the suggestions on here.

By the way I tried the curly girl method over the summer but couldn't get it to work for me at all, the frizz just got worse. I know that regular blow drying is bad for hair but perversely its the only time mine actually looks good. I try to only wash and blow dry 2 or 3 times a week, definitely not everyday