Free Windows Dictation  ( 2/28/2018 email)

Cortana cannot take dictation. But it can launch programs. You can say "Cortana launch Word." and away she goes. But Cortana can't take dictation. Speech to text. However you can go to the Windows Store (Store App) and get WriteNaturally. Free. That app takes dictation. It understands comma, period, question mark, semicolon, colon. Doesn't backspace or erase as far as I can tell. So activate the voice control of Cortana and say

Cortana launch WriteNaturally

Then click Record and dictate.

You can then select all the text in WriteNaturally's window and paste into Word, or an email, etc. Yes, you may have to format a bit.

But the tools: Cortana and WriteNaturally were free. Might be of use to you. Enjoy.