Agents deal with agents. Principals outrank them. As described in the movie MATRIX .... when you see an agent RUN!!! Or as I prefer to do present them with a business card stating that I only deal with Principals.
The carte de persona is described in the First Law of the Defendant ... don't answer until the agent proves his right to represent the principal.
So I did. Who am I going to request leave of?
A woman gave up her twin sons for adoption. One went to Spain and was named Juan. The other went to the middle east and was called Amal. Years later Juan sent her a photo. She was depressed because she had no photo of Amal until her husband told her "They are identical twins. When you have seen Juan you have seen Amal"