Microsoft 365 features that help users manage their subscriptions, account settings, and billing information.
Any chance this subscription was signed up via a third party like Apple App Store, Google play, Best Buy or Costco to name a few? If so billing management is via them not via Microsoft.
Otherwise use this instruction to get in touch with billing support.
To get help, open the "Get Help" app on your computer (just search for it in the Start menu). or go to https://support.microsoft.com/contactus, Type "Billing" and press Enter. On the next screen, click "Contact support" at the bottom of the page, then choose "Microsoft 365" > "Manage my subscription". You’ll then see the option to chat with a Microsoft support agent who has access to your account to help review the issue.