I currently have my hair tinted every six weeks with an all over tint-have tried highlights but the condition was suffering.But it is only three weeks since my most recent £70 trip to the salon and already the sides and partings are very grey.Could I patch these myself? What would I use? How would I match the colour?as the shade I have is a mix of several, and would my very nice hairdresser know I had been DIYing?