Personal loan

There was a personal loan taken from a bank 10 years back and due to financial crisis & recession the loan was unpaid. A case was filed by the bank and I was attending the hearings on a regular basis. As of a sudden the hearings stopped and later my advocate said that the bank had closed and all the cases filed by that bank were withdrawn. The bank had sold off the accounts to a pvt firm who started following up after 6-7 years and I informed that the case was filed due to various disputes and they should be filing a case again so that the settlement can happen via court. However as usual they started threatening / abusive calls to me and also to other people from my wifes friend list. There was a situation where due to this the other person filed a FIR against the bank for this activity and I also filed a complaint against them with the PVT firm who was dealing with the account. after this all the calls stopped and then later after a year or so calls started coming in from people claiming to be police officers. Is this legal. Can police officers call , I have not received any summons or any notice from any registered post / in person or have signed anywhere from my end that I showcases that I have received any such documents. Let me know next steps to deal in such scenarios