I don't know of any, but you say you want to go back to your natural color so you won't have to henna again, so why are you trying to do a henna/indigo?
I dont think many hair salons that would have hairdressers willing to risk getting henna stains on their hair.. sorry I'm not much of a help. Good luck with this though.
ETA: I completely missed that you said you're a brunette, when you said "i used to be a blonde" I thought that was your natural color. Sorry about that.