Do you have a lot of colour build up or is your hair naturally dark?
The two present different problems.
If you have build up, they might have to strip it or use an effacor to remove some colour or it will almost definitely go orange. Then cover it with a mid brown with a good shot of green ash in it to neutralise the tones.
If your hair is naturally very dark it should be possible to go chocolate (get them to get the swatch chart out - the word chocolate in terms of hair colur often has a fair bit of gold in it or even mahogany...better off saying "cool to neutral" to get your point across just in case).
If I were you I would find a reputable salon who is willing to take the time to do a couple of strand tests to ensure they are able to achieve your desired colour. Sorry I can't specifically recommend anyone.
You need a colour with the full range of tones but that doesn't have any copper, not too much gold, and if it contains gold then a violet ash reflect, no mahogany, and absolutely no "red". And a bit of green ash on the first application or an ash toner if it does throw out too much gold.
Thanks so much that is really helpful TattyDevine. That is what I wanted to say at a salon at my first salon visit bit didn't know how to.
My hair is naturally dark and has been tinted recently never being tinted before.
The problem is my hair looks orange toned in salon and indoor lighting, in dimmer lights it looks more copper/gold brown and then in natural light you hardly see brown in my hair. If sun is shining then its a bid more brown red-orange. My own natural hair shade is generally the same shade in most lighting