I've tried various shampoos and lately my hair looks really dull and lifeless and after three days is starting to look awful, whereas before it would look at its best three days after a shampoo. Could anyone please recommend a rejuvenating and revitalising shampoo - am thinking along the lines of Kerastase (sp?) or similar as have read good things about it. My hair is very thick, collar length and home dyed. TIA.