Does anyone know if Social Security funds can be attached to pay medical bills? [View all]

I got a call from the rehab facility I went to when I broke my leg, saying that I was responsible for co-payments I incurred whlle staying there. I have Medicare and Medicaid and I thought that would take care of it. She said that my Social Security payments could be attached if I was unwilling to pay. I think this smells. What do you think?