Microsoft 365 features that help users manage their subscriptions, account settings, and billing information.
I understand how frustrating it must be to be locked out of your Microsoft 365 Business subscription and unable to reach the appropriate support team.
Could you please confirm whether the subscription was purchased directly from Microsoft or through a Microsoft partner/reseller? If it was purchased through a partner or reseller, you may need to contact them directly for assistance with the subscription and billing.
If the subscription was purchased directly from Microsoft, could you please confirm whether there is another administrator account in your Microsoft 365 organization that can still sign in successfully? If another administrator has access, they may be able to contact Microsoft Support through the Microsoft 365 admin center.
If you are unable to reach the appropriate support team by phone, you can consider directly submitting a support request as another way to contact Microsoft Support:
-Create a temporary Microsoft 365 tenant using a trial license: Go to Microsoft 365 Business Plans and Pricing and click Try for free to set up a temporary Microsoft 365 tenant with a trial license.
-Use this new account to sign in to the Microsoft 365 Admin Center and submit a support request on behalf of the affected tenant.
-Select the Help & support (headset) icon >If Support Assistant is enabled, turn it off >Type contact support in the search box >Select Contact support, then choose Phone or Email to submit your request.
Note: This method doesn't require you to use your new account for your business. Instead, it allows you to create a temporary global administrator account so you can submit a support request, as your original Microsoft 365 Business subscription is currently inaccessible. The trial account is free for one month. Be sure to delete it after submitting your support request to avoid any automatic renewals or charges from Microsoft.
For further instructions, you can refer to the following Microsoft guides:
Get support - Microsoft 365 admin | Microsoft Learn.
Cancel your Microsoft business subscription in the Microsoft 365 admin center | Microsoft Learn
I hope this gives you another way to reach the appropriate support team.