Answer
(Fatwa: 466/333=L/1430)
What the aamil says is not authority; therefore it is unlawful to believe that they have done you magic with the help of Hindu priest. But, if you like to enquire them you can do so and if needed you can ask them to take oath as well. If they deny and take oath, then only by saying the aamil you are not allowed to term them as liar and suspect about them, as Allah says:
?O you who believe, abstain from many of the suspicions. Some suspicions are sins.? (49:12)
Allah (Subhana Wa Ta’ala) knows Best
Darul Ifta,
Darul Uloom Deoband