I have some grey hairs mainly around my temples which to be fair, are only visible when I put my hair up or in a pony tail (which I do alot as I do alot of gym & running etc). I colour it myself with a permanent colour (Clairol root touch up) mainly to save expense of colouring by hairdresser which is rather expensive for me. Some of the grey is totally resistant to the dye - anyone find this - that some grey hair simply will not change? thank you