Harassments from sbi card recovery

I have received call from SBI card recovery. They mentioned that it is regarding some amount pending on my Dad's credit card. They mentioned that the credit card was issued in the Year 2001 and since the year 2003, there has been an outstanding amount of Rs.7500. My Dad has expired around 2 years back and as far as I know my Dad never used any credit card. These SBI card recovery people called me and started abusing me to repay that so called outstanding amount of my Dad. They even called my Mother (Don't know how do they get the phone numbers of family members) I request the honorable and respected members of this forum to guide me in this case as to what legal steps should we pursue to stop this harassments from these Recovery people. We are not at all liable for any outstanding to SBI card Thanks and Regards