Getting hair back to its natural colour?

My hair is dark brown, with pretty strong natural highlights. I've dyed it both a black and a burgundy colour before, and then I tried to get my natural back. I never bleached it or anything between dyes, so it always looks miscoloured. Is there any way to get the natural back, can a salon do it, or even some other remedies I can do myself that work to take dyes out and such? Anything would help.