T.W.
I have dark brown hair with highlights and awhile ago I decided I wanted to go back to my darker shade. My hairstylist did a "color gloss" which darkens the highlights but they still remain a touch lighter than your natural shade, it looked really natural and you could barely tell I had roots as it started to grow out.
I'm sure your stylist can do what you want so long as it's a decent salon, I doubt you'll need to book more time either. goodluck!