Deceased estate

My mom passed away earlier this year. I thought the right thing to do was inform STD Bank. The next thing I get a lawyers letter collecting the amount outstanding. I get monthly calls about going to the court and getting a letter stating there is no will, estate or executor. I have requested that I don't get calls, that I am not going to go to the court but yet the calls keep on coming in on a monthly basis. Std Bank not once made contact with me to discuss this matter yet have to go. Why was my mom not offered card protection, and if she was offered and did not accept surely she had to sign as confirmation. Her card was renewed, surely there had to be some sort of form she signed. If I am not mistaken STD bank had to keep record of this according to the FAIS ACT. Earlier in Nov ' +- 10 I phoned thecomplaints dept and a service request was sms'd to me with a due date, till now I have had NO reply from STD BANK. I got advise from a attorney that legally I am not obliged to do anything. I am not impressed with the calls I receive during my working hours. I did not sign surety and I am not responsible for my moms debt. Kindly resolve this matter once and for all.