What happens if I change plans and request automatic premium deductions from my Social Security benefits for my new plan, but the premium deduction from my previous plan doesn't stop?
Social Security cannot process your request for automatic premium deduction for your new plan until the premium deduction for your previous plan is stopped. The request from your new plan will be rejected if the previous premium deduction hasn't been stopped first. Your plan will need to contact Medicare so they can find out why the new action won't take effect.
(Source: U.S. Department of Health & Human Services)