Maybe I wasn't clear*: I was a member of Commonwealth Care (which is Massachusetts public health insurance) with $40 premiums. Then I received notification from the feds that I would be automatically enrolled in Medicare A and B with >$100 premiums since I was on SSDI. Around that time, I was also notified by Commonwealth Care that I cannot keep both insurance plans (you cannot keep both Commonwealth Care AND Medicare). Commonwealth Care is cheaper, so I (called Commonwealth Care and) asked how I can stay on Commonwealth Care. Commonwealth Care told me that if I cancel Medicare, I can stay on their plan. So I called Medicare and asked to cancel, and sent in a cancellation letter as advised in that call. (At this point in the story, no one had mentioned yet that cancelling Medicare A means cancelling and paying back all SSDI benefits.) Weeks later, I find out that Medicare B was cancelled but not Medicare A. I'm puzzled about why. My first concern was that I might have lost Commonwealth Care. So, I called Commonwealth Care and found out that my Commonwealth Care plan was indeed cancelled because their database (which is shared with the feds) showed that I was enrolled in Medicare A. Then I called Medicare and found out that I cannot cancel Medicare A without losing and paying back all SSDI benefits (this news is completely new to me). I also learn that Medicare A only covers hospitalizations, and does NOT cover regular doctor's visits. Thus, I am stuck without any insurance that covers normal trips to the doctor (that don't involve being "hospitalized"). No Medicare B AND no Commonwealth Care.

Hope this makes sense now!

*Health insurance plans mentioned in above:
Commonwealth Care = Funded by State of Massachusetts
Medicare A = Federal Funding, ONLY covers hospitalizations (NOT regular doctor's visits)
Medicare B = Federal Funding, covers doctors visits