A group of Microsoft Products and technologies used for sharing and managing content, knowledge, and applications.
Hello @MSM,
First, I need to clarify that as a Microsoft Community Moderator, I don't have the ability to escalate cases on a customer's behalf.
If your Microsoft partner opened the existing support ticket for you, please ask the partner to follow up on that case through their support channel.
If you opened the case directly through the Microsoft 365 admin center and the existing case is no longer receiving a response, I recommend create a new support request and reference the existing case number. In the new request, provide the existing case number and clearly explain that the issue is business-critical, you currently cannot access or back up the affected OneDrive and SharePoint data, and the existing case is not receiving a response. This will give the support team the context needed to review the situation.
Thank you for your understanding.