What do you do in the case of a paternal cousin's daughter possessed by a jinn who speaks through her and refuses to leave, claiming to love her, especially since taking her for ruqyah has been repeatedly fruitless?

The treatment for a case of demonic possession is through Ruqyah Sharia (Islamic exorcism), along with adhering to several matters:

1. Persevering in remembrance (dhikr), especially reciting the Quran (Al-Mu'awwidhat, Al-Fatiha, Al-Baqarah, Ayat Al-Kursi).

2. The Ruqyah should be performed by a righteous reciter who adheres to the Sunnah.

3. Frequently turning to Allah Almighty in supplication (dua), especially during times when prayers are answered.

4. Maintaining the five daily prayers at their prescribed times.

5. Repenting to Allah Almighty from sins and transgressions.

6. Purifying the home from what the devil loves, such as pictures, dogs, and music.