How can jinn serve humans, and do the actions of the man who claims to undo magic by producing objects from thin air constitute sorcery and deception?

The use of jinn by humans is possible and real, but its legal ruling varies. It appears that prohibition is more appropriate to prevent the practice of magic and mischief, especially since the Prophet, peace be upon him, his successors, and the Companions did not do it. What the mentioned man is doing with your aunt is a type of magic, and one must be wary of it. Treatment with legal ruqyah, performing acts of obedience, and maintaining remembrance (dhikr) are sufficient.