Estate and Credit Card Company

My mother passed away about a 6 weeks ago. She had about $20,000 on one credit card. I have received an Asset Collection agencies letter yesterday in the mail. Her assets (just a few hundred dollars) are already dedicated to bills (medical and legal already). How should I respond to the credit card collection letter? Should I just send a note with the Probated Will letter (making me Executor) stating the assets are already exhausted? Please advise.

I think this is an article that may help you with your current situation: Creditor Claims on an Estate Lawyers