Loan recovery

My deceased father had taken a personal loan which we weren't aware about, the application form he submitted did not include our details. The loan was taken on 2019 and was for a period of 3 years, in the statement provided I saw an insurance installment which I believe is to cover the loan taken as there was no collateral. The recovery agents are calling themselves employees of HDBFS (from where the loan was taken) and have been harrassing my mother who is a senior citizen to repay the loan. My mother or any of the family member were not the guarantor or the co borrower of the loan, but yet they are pressuring my family to pay the settlement amount. We are repeatedly asking for documents like loan sanction letter, disbursement letter, approval letter, guarantor details, insurance details to validate if the loan was taken and to understand the terms on which it was taken all they could share is an application form and they mention they cannot share it on email id since it is not registered email id but on the contrary can call us even if our number is not registered. All the communication is happening on Whatsapp if we ask for official email id they mention that they cannot give us the same. Since we are unable to visit the bank they are ready to send bank executive to collect the settlement amount but cannot send the documents with the executive. They are asking us to visit the branch for the documents. Legally I don't even know if I should be clearing the loan amount, please help me on this