A Microsoft offering that enables tracking of cloud usage and expenditures for Azure and other cloud providers.
No worries @Brian Lynn and sorry to hear about the support ticket runaround.
I've had a similar experience myself where I couldn't remove an old card from my personal account (https://account.microsoft.com/billing/payments?lang=en-US#main-content-landing-react) because Azure was referencing it. I realize you stated you don't have a subscription, so this may or may not work but it's worth a shot.
What I did to resolve my issue was updated the payment card on a PAYG subscription I have. Sign into https://portal.azure.com/?pwa=1#view/Microsoft_Azure_Billing/SubscriptionsBladeV2 with your personal MSA that has the expired card. If you see a subscription listed, you can either replace and (or) cancel the subscription. I suggest replacing because this will help you confirm that you can remove the old credit card from your MSA.
However, if this doesn't work, and you didn't see a subscription listed then let me know the steps you took for opening a support ticket.