Hair coloring question?

I was lighting my roots regularly every 3 moths at a hair salon, then I decided I wanted to go back to my natural hair color which is brown. I went to new hair salon and the color that came out was horrible. Out of panic I went to my old hair salon and begged them to lighten them up again. In result I lost a lot of hair, they are now ugly and severly damaged. My question is, when will it be safe to go back to my dark hair again? Will darkening the hair cause even more damage or will it help my hair? How long should I wait? (I lighten them 1 month ago) Or should I just leave my hair alone and if yes, for how long?