Is it permissible to accept help from a Samaritan man who claims to solve problems and practice magic, in order to undo alleged magic, or is it obligatory to put one's trust in Allah and not resort to such acts?

The man mentioned is a soothsayer (kahin), and the things he told you that actually happened are due to the fact that soothsayers have companions from among the jinn (devils) who inspire them with information they eavesdrop on concerning matters decreed in heaven. When Allah decrees a matter in heaven, the jinn who eavesdrop hear it and relay it to those beneath them until it reaches the sorcerer or soothsayer. The soothsayer may then add a hundred lies to this one truth. The Sunnah has forbidden believing soothsayers or visiting them. Whoever comes to a soothsayer or diviner and believes him has disbelieved in what was revealed to Muhammad. And whoever comes to him and asks him about something, his prayer will not be accepted for forty nights. Therefore, it is not permissible to believe this man or to visit him.