Sole admin locked out of Azure tenant - Authenticator MFA lost after phone change, can't open a support ticket

Hi,

I'm the only admin of my Azure tenant and I'm locked out because of MFA.

I sign in with a personal Microsoft account. The password works and the account itself is fine, I can sign in to account.microsoft.com without problems. But when I open the Azure portal, the tenant asks for the Authenticator code. That's the only MFA method I ever set up there, no phone number.

I got a new phone and restored Authenticator from a backup. Since then I don't get any push notifications for this account and the codes are rejected. The old phone is gone, so that doesn't help either.

I tried to open a support request, but the form at support.microsoft.com/oas sends me straight to the same MFA prompt. I also tried with a second Microsoft account, but that one has no tenant, so the portal won't let me create a support request (AADSTS16000).

There's no subscription in the tenant anymore, I cancelled it last year.

Is there a way to get the MFA reset for my account, ideally in writing? I can send the tenant ID, billing details and an older support case number by private message.

Thanks