How can I stop my black hair colour fading?

I had blonde highlighted hair which I died black, and it looks great. The only problem is that where the highlights were some of the black hair dye is going a dark brown!! Why is this? And how can I stop it?





I only dyed it last weeks so I don't want to dye it again too soon, is there anyway I can stop the fading or will it just stay as it is?





Will it be ok to use one of those wash in toners things to darken it back down?





Thanks


xxxxHow can I stop my black hair colour fading?
Yes , in between shampoos are great,I think there is one by Redkin. Also if you have it done at a salon you can ask to have them use a ten volume developer, and that will make it only deposite, also comb the color through once applied...Hope that helps.How can I stop my black hair colour fading?
But toners will not darken it back down. I had ash blonde highlights once and dyed my whole hair black. It started to fade and it turned GREENISH. I think the toners might make your hair green instead. I'd say don't touch it. It's only natural that the highlighted areas of your hair are brown instead of black, because they were lighter than the rest of yr hair in the 1st place.
i dont know