Microsoft 365 features that help users manage their subscriptions, account settings, and billing information.
Hey there! Nice to meet you!
Please be advised that unless the account owner is able to access the account, subscription cancellation is not possible, and Microsoft personnel cannot retrieve this information.
Since you mentioned: "old and now defunked emailaddress" if you are no longer able to recover your account, you will need to reach out directly to your bank and request to freeze all charges from Microsoft, cancelling the subscription on its renewal in the process.
Then you will also need to request a new payment method from your bank.
Thank you for your understanding.
Best regards,
Darhyl