Why does my copper hair turn black ?

When I want a nice medium rich brown? I want to cover up the light and darker copper on my head along with the brassy blonde on top but when the stylists do test strands they turn out much too dark. One side I may need to go permanent rather than demi but i do not want to do that because my hair so fried. I even have permanent low lights on one side so I finally said maybe you can just add some lowlights (demi taht is) to the other side to even them out because then from a distance it looks like my hair is medium brown rather than copper and dark brown mixed. I figured if I cannot have medium brown then the dark brown they do they can foil all over while keeping some copper that way the brassy not be so brassy and overall color not so dark. But she told me she canot do taht as the demi soaks up fast in my porous hair and she cannot go fast enough to do the whole head before they become too dark. Any ideas what to do? I worry if I buy ash it will make my hair too dark and/or too green since it is so processed. I had bough ash blond in loreal color gems from Sally as i was told to go lighter. But then I was told that blond anything will not cover. So now i just dont know what to do. there is in the demis clairol color instincts and loreal colorspa but what color to use? If I temporarly used clairol jazzed I do not know what color in that semi perm line as they are all kinda odd. But I gotta do something! my hair is way darker on one side. Any ideas? Thanks. 

Thank U. What is a protein filler? Why has no stylist recommended it? I swear I think most stylists in my area are just not that good I have been on so many consults and none will tell you your hair is beyond their level of expertise either. Most of my color is from last summer so I wonder if it can still be stripped? And even if I find someone who used Phantom Modulat or one of those supposedly less damaging color removers, how much damage would that mean? Thanks...

If I was you then I would go to sallys and get...

-a porosity equalizer (usually located near the perms)

-a neutral protein filler.

-and a ion hair color in light golden brown with 20 volume.

-and a wella demi-perm hair color in lt neutral brown.

First shampoo and towel dry your hair, then apply the porosity equalizer and comb thru. Then apply the neutral protein filler and leave on for 20 min, after the 20 min is up towel blot the excess filler and then apply the lt golden brown, and leave it on for 30 minutes. This will leave you with a med-lt golden brown, if the gold bothers you then apply the demi-perm lt brown for 20 min, this will reduce the gold tones. This process will leave you with a natural looking hair color, and the ion and wella color's are both very easy on your hair. It is important that you apply a filler every time you color your hair until it is no longer porus, so make sure you always apply a filler, or your hair will come out too dark!