Partner lockout of Microsoft 365 tenant – looking for advice on next steps

Hello Ermserg,

That's a tough spot. Luckly i haven't been or seen this kind of thing happens before, but here is what you need to do quickly as this indeed could lead to data breached. 

On the Microsoft side:

The fastest way to get them off your back is to call Microsoft Support directly and open a high-priority ticket. Make it clear it's a security incident involving a partner misusing their delegated admin rights. Microsoft takes that stuff very seriously and they can forcibly remove that partner's access. Don't wait for the Business Conduct team to reply to an email—a phone call and a support ticket will get you a person much faster.

Prepare the documents as they might request a proof of the domain.

As for the legal stuff:

This is a huge red flag and a clear violation of the Microsoft Partner Code of Conduct. They are holding your data hostage over a billing dispute, which is absolutely not what delegated access is for. It's also a major GDPR issue is indicated by Microsoft. 

https://learn.microsoft.com/en-us/partner-center/security/nonpayment-fraud-misuse

Check in your country to see if there are any organizations or government associations that could assist and guide you with the legal procedures.

My two cents:

Focus on the technical fix first, but get your legal team involved right away. Document everything. Hope you get this sorted quickly.