Adventures in hair color

I have wonderful friends, but they have GOT to keep me from trying to color my own hair. I was very disappointed in a recent highlight job, which I paid for. I swear, I thought I was playing it safe. I bought "Light Brown" #6. Light Brown! Not medium brown. What I have ended up with is VERY dark brown! Now I have to wait to have it fixed so that I don't make all my hair fall out!