DCM Services, LLC review: Harassing calls and letters 1

I just received a letter in the mail regarding my late Mother's outstanding bills from DCM Services. She passed not even 2 months ago. Wondering what company they do collections for, I did some research online and see that the majority of people are saying it's for Discover card. My Mom HAS NEVER in her life had a Discover card. I called the number off the letter and explained this to the rude lady on the phone and she basically called me a liar and asked ME to pay off the balance! I explained to her again that there is no account with Discover, and I sure as hell know that I am not held responsible for any outstanding debts owed. Look lady, I understand you have a job to do, be it as crappy as it is, but you're NOT listening to me! Never once did she ask for a copy of the death certificate which only confirms the fact in my mind that this is not a legitimate letter and a scam.