Disclaimer: This platform is in Chinese (Traditional). However, I noticed that your message was written in English, so I will respond in English to ensure clarity and provide better assistance.
Dear @Vincent Su,
Good day. Thank you for posting your question in the Microsoft Q&A forum!
According to your description, I understand that you're experiencing issues while attempting to purchase Microsoft 365 Business Basic, as the registration process cannot be completed because the domain is marked as already in use.
In this case, the best course of action is to contact Data Protection directly.
For a full list of regional numbers, you can also visit this official page: Customer service phone numbers - Microsoft Support. The support team will assist you as soon as possible.
If you can reach Microsoft by phone, use the official Global Customer Service phone numbers list. Choose your region > your country > if your country lines fail or lack English support, select a nearby country (e.g., Singapore) or the United States number, Microsoft explicitly allows this.
Since you cannot access the Microsoft Admin Center, you can try set up a new trial tenant and submit your support request:
1.Visit the Microsoft 365 Enterprise Plans page: Go to Compare Office 365 Enterprise Pricing and Plans | Microsoft 365.
2.Choose a plan and start a free trial: Select any of the available plans and click "Try for free" to begin the trial setup process.
3.Follow the guided setup: Complete the steps to create a new Microsoft account and a new tenant. This will be a separate and independent Microsoft 365 environment.
4.Access the Microsoft 365 Admin Center: Once the new tenant is created, navigate to https://admin.microsoft.com/AdminPortal/Home#/homepage
5.Go to Support: In the left-hand navigation menu, click on "Support" and then "Help & support."
6.Raise a support ticket: Describe your issue in detail. Crucially, you must clearly state that you are locked out of a different, pre-existing Microsoft 365 tenant where you are the administrator. Provide the following information about your locked account:
- Your administrator account email address for the tenant.
- The domain name of your tenant
- Any error messages you are receiving.
- Details about the issues you are experiencing (e.g., update banking information).
- Confirmation that you are the administrator of the tenant.
7.Submit your ticket:
Follow the prompts to submit your support request. You will likely receive a ticket number for tracking.
Important notes:
- This new trial tenant will not give you access to any of the data or settings in your original locked tenant. It is solely a temporary means to contact Microsoft support.
- Be prepared for Microsoft support to ask for verification of your identity and administrative rights for the locked tenant.
- The resolution time might be longer as you are contacting support from a different tenant.
- Remember to cancel the trial subscription for the new tenant once your issue with the original account is resolved to avoid any unintended charges. You can typically do this within the Microsoft 365 Admin Center under "Billing" > "Your products."
I hope these steps will help resolve your issue. If you need further assistance, I am always here to help.
Thank you for your patience and understanding. I appreciate your continued trust. Hope you having a nice day and really much warm regards to you as well!
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