Hello @Richard Wilson
Welcome to the Microsoft Q&A Community!
I completely understand how stressful and discouraging this situation can be, especially when you're unable to reach the support team you need, and access issues are blocking your next steps. You're doing all the right things, and I’m here to support you through every option available.
To help move this forward, the most effective path is still to contact our Data Protection Team, as they’re the only group who can assist when global admin access is lost. Please find the appropriate contact information here and try calling 2-3 times during work week: Customer service phone numbers - Microsoft Support
A quick tip to help you reach a real person faster: Depending on your region, you may hear an automated introduction for about 30 seconds, such as “you can visit the link…”. Please ignore this introduction and wait until the options appear.
- Press 1 for business email user
- Press 1 again for technical help
This will route you to an agent who can open a Data Protection case on your behalf.
Once connected, kindly explain that: Your Global Admins are completely locked out. You need Data Protection / Account Recovery assistance to verify ownership and restore access
If you cannot successfully speak to a support representative, please consider creating a new tenant by signing up for a trial Microsoft 365 subscription via this link Compare All Microsoft 365 Plans | Microsoft. 
Once the new tenant is set up, use its admin console to submit a support ticket requesting assistance for your original tenant. Remember to cancel the trial subscription after the issue is resolved to avoid charges.
Thank you very much for your valuable time and your cooperation. Let me know how it goes on your end or if you need further assistance.
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