How I can block sending message to # 00447786205094

This SMS is an SMS to the Apple server in the UK for the purpose of activating iMessage and FaceTime. If you are using a supported carrier for the iPhone, then those carriers normally do not charge for that message if they support iMessage and FaceTime.

Is it possible that you are not using a supported carrier for the iPhone?

Turn off facetime and iMessage. That is Apple's activation server for Facetime and iMessage. If you were using a supported carrier, you would not be charged for these. If you ARE using a supported carrier, and still seeing charges for these, contact your carrier and make sure they have your account provisioned for an iPhone.

This is either for iMessage or FaceTime.

You can switch both off if you want.

If you are using a supported carrier for the iPhone, they are supposed to have an agreement with Apple not to charge for this SMS. I suggest you contact your carrier then to have them refund this charge, or at least to answer why it is that they are charging for it.

Which carrier is this and where are you located?

Then contact them and make sure they know you have an iPhone. They are a supported carrier. They should not be charging you for those... but you need to tell them you have an iPhone and make sure your account is provisioned correctly.

How do i block them

That is the number used to activate iMessage and FaceTime. You are going to have to turn off iMessage and FaceTime to stop that.