I'm a brunette who went blonde. It's a honey blonde and it took differently in different parts of my hair. It's lighter in some places but not others. The places that didn't lighten as much are a little too bright and yellowy for me. I want to use Prell to lighten it like I've heard it lightens black dyed hair to brown, but does it work on hair that has been dyed lighter? I dyed my hair at a salon and don't have the money to go back. No Sally store in the area. HELP!