West Bengal Police — mobile phone harassment

Address:

Birbhum, West Bengal, 731204

Dear sir/madam,
I am getting continuous harassment call in abusive language on my mother's mobile number from this number ([protected]).
I checked from truecaller this number perhaps belongs to swapan from haltu bazar.
The person is saying that this number belongs to him which is lost and robbed from him.
My mother taken this sim from an authorized dealer and she don't know anything about it. I also failed to make him understand that mobile operators issues same number if the number is inactive.
But this person however fails to understand it and abusing her continuously, please take immediate action to stop this nuisance.