soothsayers

Dear Scholar,Assalamu Alaikum.A relative of mine recently went to a magician/soothsayer who has 'special knowledge' about magic (without my knowledge) and found out that I am under the influence of black magic. I understand that to dispel the black magic it is necessary to increase dhikr and dua. However, in addition to this, in my country it is common practice to also ask magicians/soothsayers to dispel the magic through the use of their 'special' knowledge. I was wondering what is the Islamic view on such practices?  Many people also recite surahs onto water and then give this to drink to rid the effects of black magic. Is this practice correct? And as far as I understand it is not correct to go to these magician/soothsayer, so what is the correct Islamic method of finding out whether one is under the influence of black magic? If an individual recites extra surahs and makes dua does it rid the effects of the black magic completely?Thank you for answering all of my questions!