Used ash blonde color...hair turned brassy?

Today I used a box of very light ash blonde hair color on my hair to lighten it up a bit. My hair had been previously highlighted at the salon (4 months ago).

The highlighted areas turned a beautiful light blonde, but the rest of my hair turned an orangey/brassy color, despite using the ash tone.

I'm a little stuck as to what to do. The color isn't awful, but the orangey tones are making my skin look really red :(

Can anyone suggest which direction I should go in? I was considering just getting some dark blonde color and putting a few lowlights in to break up the brassyness...but I am not sure if that's a good idea or if I should get a toner instead?

Thanks!

I agree with jenners1984,  i love the clairol shimmer lights shampoo and conditioner!  you can also try a toner.  or, just pure real lemon juice, and go out in the sun.  it will naturally lighten up and cast out and  brassiness out of your hair.  i would apply the lemon juice every time you wash your hair.