Administrator Role Needed

Our organization had a third-party administrator set up our Microsoft Profile for Azure Activity Directory, Office 365, and SharePoint. The administrator is no longer supporting our account on their server and has the only Microsoft login with administrator privileges. They have disabled our access to most functions without giving us a mechanism to update billing or transfer all files.
Although the vendor disabled our server access, automatic monthly payments to Microsoft were being withdrawn from our bank. We were able to maintain our account and access to OneDrive files until our billing method was compromised. I am unable to update our payment method which has caused us to lose the ability to access OneDrive files from the past month. I have tried creating a support request via Microsoft but am giving the message, "Switch to an account that has permission. Your account (xxxxx@Amir .org) doesn’t have permission to view or manage this page in the Microsoft 365 admin center."