Hi Voodoo man!,
I’ve actually just purchased a Servitor the other day. I haven’t used it just yet as it isn’t ready but I’ll be happy to keep you posted on updates when I do get it.
In the article on this site about them, they say communication with the servitor is verbal but you should also mentally imagine what it is you desire.
You can scroll down to the blue text that reads “How do you communicate with Servitors”. If you haven’t already read the article, give it a read! It answered a lot of my questions 🙂
I’ve received my Servitor!
I have verbally introduced myself to it as its Master and also named it.
The email that is sent when your servitor is finished also has more info on communicating with it; verbal, mental and emotional combined are the best method.