I do not understand how medicare works. Company A was handling all of my mother's medical billings, I paid co-pays. Company B took over company A. All I knew was that her health insurance card changed, I did not realize that a premium was involved other than what is taken out of her SS check. Now company B says that mom owes $565 for premiums payments from the begining of this year. What are they talking about. They sent me a booklet about their insurance but I do not understand it. I want medicare part A and B and D for drug coverage. What else should I consider? Mom live in a private pay memory care home with 3 other adults.