I seem to recall paying for my quarterly Medicare premium with a credit card prior to having it deducted from my SS.
If so, it was apparently changed. The "Medicare Easy Pay" system now only deals with bank accounts.
https://secure.ssa.gov/poms.nsf/lnx/0601001025A completed credit card payment request must be submitted each month a payment is to be processed. Automatic payment by credit card is not available at this time.