I do not understand your train of thought at all.

Those people want control, they want you to listen, they want your attention.
Usually it drives them up the wall and makes them mad as a hatter if you ignore them and do not pay attention to them.

To me, ignoring them and not paying attention to them is the most powerful thing you can do.

Every letter you get and throw away and every Email you delete without reading is more power to you.
Because it is not them who wield the power, it is not them that control you. You are in charge.

But besides that, they should not have your email address or telephone number in the first place.
They will never listen if you say "I do not want you to contact me!", it is not how these people work, they never are gonna change.