Hi Thomas Oettli,
Thanks for reaching out to Microsoft Q&A.
Try with any one of the below options that could help you.
You can reach out Azure billing and subscription management team by creating a billing support request. Billing support requests via the Azure portal is free for all Azure customers and doesn't require a paid support plan. Please select 'Billing' under 'issue type' while creating the support request.
https://azure.microsoft.com/en-in/support/create-ticket
Reactivate a disabled Azure subscription:
https://learn.microsoft.com/en-us/azure/cost-management-billing/manage/subscription-disabled
Reach out to Customer Service (global) phone numbers:
Please 'Upvote'(Thumbs-up) and 'Accept' as an answer if the reply was helpful. This will benefit other community members who face the same issue.