Sims & Assoc

My D-I-L called from another state and said she had a message on her machine for my mother who passed away in June 2012. She gave me the info and I call this Mia Anderson with Sims & Assoc and she starts asking about a credit card bill for my Mom. I said I will need proof of debt including a complete itemized statement of account showing all charges and any fees that may be getting charged. She says we do not have that considering this is an account with the LAST PAYMENT being made in 1998. I said have you lost your mind? Trying to call family who lost a loved one less then a year ago about a debt from 1998. So now I am going to send a cease and desist letter to them, but do not want them to have my full name. So think it will be valid if I just put the Family Of ??
Also I am thinking about giving them a forwarding address of the cemetary and also Heaven. Is there anything else I can do to stop them from calling everyone throughout the US with the same last name as her and saying they are calling for her. I have been called about this from other family members too. So they are calling around.