A.L.
Morning
If you haven't tried this already.. there are shampoos that have color in them, I USED to use artec when my hair was on the redder side.. It takes a couple of shampoos to amp up the color... then if you want to change it out, you wash it a few times... Also, the Artec can be used in conjunction with hairdyes.. so if you do dye your hair and the color starts to look dull, you can use the artec to give it more vibrance... this is one way of getting color..
the other. I used naturtint.. it's easier on the hair than say loreal or sally... (at least for me) I like it because it's not a strong, covers grey and although this part I don't necessarily like, it doesn't stay quite as long as other stronger dyes..but then again, i don't want the something too harsh..
I use a med to light brown... after about two weeks, it does lighten up quite a bit... not to blonde... but at least one shade lighter of brown... so this might be something that could work for you..
good luck