Neighbour woman Aarthi working in Infosys doing black magic and harassing me

How can I get legal help against black magic done by the neighbours who are obsessed with buying my flat. They have been doing spells on my flat for 1.5 years and are now doing black magic on my food brought in by Swiggy delivery. The woman Aarthi SS works in Infosys Chennai and has been obsessed with my flat since she moved into the adjacent flat in 2017. She and her family repeatedly asked my Mum and me to sell the flat to them despite our outright refusals. I had reported her to the police last year in December when I saw her black magic stuff in our postbox. She, her husband Balasubramanian and daughter ran away like rats at the mention of police and slunked back after the police had left. Her old parents Subramanian and Kanthimathi too are actively involved in black magic. I have a good mind to report them to the district collector and city police chief with a copy to her HR department in Infosys, but not sure how something like black magic can be proved, despite all the packets of ash and chilles and lemons and sigils and spell water they have been leaving outside the flat and in the postbox and my car. I would appreciate any legal advise.