Is this translation correct?

Hello, does どなたですか? mean "who are you?"?
If it does not could anyone be kind enough to tell me what it does mean?

I think it's more polite way to ask someone who he is. Usually who are you in Japanese is あなたは誰ですか. どなた or どちら様 is used for 誰 in the polite manner.

Yes, "donata desu ka" is a polite way to ask "Who are you?" "May I ask who I am talking to?"
We wouldn't say "Anata wa dare desu ka" to begin with, unless you are in a confrontational situation :)

BTW, どちらさまでしょうか？ is more polite, I think.
あなただれ？ is used bluntly, maybe speaker is irritated.