If you have an admin MFA issue then only phone support can help and ask them to escalate your issue to the data protection team.
Here are some tips and an example of a prompt to help you navigate the IVR more effectively:
In some countries, it is an automated conversation like: First, when you call the hotline, it will be asked as follows:
IVR: What kind of problem are you concerned about?
You: Authenticator.
IVR: What kind of product do you use?
You: Office 365 for business.
IVR confirmation: education or company account?
You: For companies
IVR: Are you an administrator?
You: Yes.
IVR: Do you have the other administrator in your organization?
You: No.
IVR: Do you need a... Service request?
You: Yes
You also need to provide your subscription purchased information such as company name, billing information, phone number etc. See: https://learn.microsoft.com/en-us/microsoft-365/admin/get-help-support?view=o365-worldwide#phone-support