Sole Global Admin locked out of Microsoft 365 tenant, Authenticator MFA stranded on old phone, urgent

I'm the sole Global Admin for a small UK business's Microsoft 365 tenant and I'm completely locked out. This is business critical.

My Microsoft Authenticator MFA was registered on a phone I no longer have. My current phone shows the work account only as a "connected account" (used for signing into apps like Outlook/Teams), it was never registered as a verification method, so there's no working code or push notification available to me at all.

I've tried the standard UK support lines (0800 026 0329 and 0344 800 6006), but these route to an automated system that opens an email ticket rather than reaching a live agent. I've replied to that ticket asking for urgent escalation to the Data Protection/Tenant Recovery team. I have no other admin on the tenant who can help.

Could someone point me to a faster way to get this actioned, or flag my ticket for the Data Protection team? I have billing details, domain ownership access, and company registration information ready to verify ownership.

Thanks in advance, this is urgent as it's blocking all admin access to our business email and Teams.