Do you have durable POA? I sure hope so because it sounds like your mother has reached the point where she can no longer conduct her business in a business like manor which means that in that sense of the word she is incompetent and you need to step in. It would help if her doctor and particularly two doctors if possible would evaluate her and create a notarized statement saying that in their professional opinion she can no longer conduct her business in a business like manor and thus incompetent due to _____ medical reasons. Once you have enacted this POA, please contact the credit card people to explain what is going on. They will request a copy of your Durable POA which is standard operating procedure. I wish you good luck!.