Is the repentance of one who committed major polytheism by going to soothsayers and diviners accepted, and is he required to re-utter the Two Testimonies?

It is forbidden to go to soothsayers and diviners. Those who go to them are divided into three categories: 1. Forbidden: One who asks the soothsayer but does not believe him. His punishment is that his prayers will not be accepted for forty days. 2. Major disbelief (Kufr Akbar): One who asks the soothsayer and believes him, because he has believed the soothsayer's claim of knowing the unseen, and this is a denial of the Qur'an. 3. Permissible: One who asks the soothsayer to expose his true nature and falsehood to people.

The door of repentance is open for every sin, and whoever repents with sincere repentance, Allah will accept it from him, even if the sin was Shirk (polytheism). There is no need for one who repents from major disbelief to re-pronounce the two testimonies (Shahadatayn) if he has already repeated them after repentance.