Paytm postpaid - Paytm postpaid fraud

My father was scammed by a person who came at our shop and told him that he is Paytm agent and has came for kyc so he gave him his mobile and he took the Paytm login in his mobile and did the transaction on the other day. This transaction was not notified by Paytm through any means not even any notification arrived and not even any message arrived and as my father is not educated so he was not aware untill I came to my hometown after ** days which was too late to file complaint against that person.so I informed this to Paytm they told me to mail the details on cybercell@paytm.com but there was no resolution from there side and also called on Aditya Birla finance number these guys said to mail them the details so I did that too but these guys also didn't helped.and these guys have hired some local people who are giving threat messages continuously and have also increased the amount to be paid to ***** which is completely unfair to me. I need justice for myself and my father. I don't want to pay this fraud transaction amount and want compensation of * lac rupees from Paytm or Aditya Birla finance for complete harrasment since * months by messaging continuously on WhatsApp.