Bank loan debt recovery issue.

My mother took a personal loan from HDFC in 2017 but later in few months she expired because of cancer. I am the only legal heir of hers since she was divorced. Loan background: Loan amount sanctioned was 7.5 lacs but only 3.5 lacs were credited in the account. The other half was supposed to be in a DD addressed to FULLERTON (to cover an old loan of 4lacs) but soon after my mother expired and the DD never reached me or the FULLERTON bank for the loan closure. as a result I had to arrange the money and closed the Fullerton loan from my own funds. Afterwards, Different officials from recovery agencies started calling me ro pay out the money and telling me to give the emi and afterwards they will give me a settlement amount for loan closure. i paid 6 EMI'S of 16000/- in 2018 but never received any closing instruction. Iwent to bank for DD enquiry but they had no idea where the DD is, and apparently the bank has misplaced the DD of amount close to 4lacs. again from past two years they are repeatedly contacting me in a interval of few months to payout the whole 7lacs amount. 1 incident happened in which a person from Delhi ITO hdfc branch asked me to send my id proof, death certificate,and 2 affidavits to close the loan account . i couriered them the documents but afterwards i never received any reply. apparently someone called me saying he is commissioner from delhi branch and case has been registered. Someone saying he is advocate in patiala house court delhi says the same. What should I do? from past 2 years im receiving these calls and as soon as i ask them about the dd, i stop getting any significant response. what they say is ok we are deducting dd amount. u can pay 3.5 lakhs instead of 7lakhs. now there is name and number of my mother 's friend on the loan paper as a guaranter and they have now issued a notice against her aswell that she will also have to pay and are threatening to register a FRAUD case against us but my mothers frnd claims she had no knowledge of her name as a guaranter in the documents. even i came to know just today about this. I've had a conversation with the advocate who has filed the complaint on behalf on the bank. He has told me that the FIR has not been filed yet but the case is on the way to get filed. I have a few questions and was hoping if you could help me out with the answers. 1. Is the guaranter liable to pay in case of the non payment of the dues from my side? Can a case be registered against the guaranter? 2. Can the FIR be actually filled for this or this is just a hoax to give a scare? 3. If yes, In case the bank goes with the FIR, then what will be the future of the case? is there any chance that the case can settle in my favor? Since the bank is not providing me any information regarding my case and repeatedly threatning me, harrasing me mentally from past 2 years, with me living alone and with no financial help now ,should I move forward nd complaint to rbi ombudsman?