Broken Account Recovery (discontinued product)

Hello everyone,

We have the MSFT Office Family plan which has the now discontinued custom domain support that used to be an option as a "Premium" feature. Back in August we upgraded the phone of one of the account members on the family plan and lost connection to their MS Office account with the only device that was accessing to the account (the phone with access was reset as part of the upgrade/trade in process). I have tried the account recovery form and it simply doesn't work. I have tried to explain to MSFT support that the tool is broken but can't get anywhere. For the account in question we have an Outlook email client (with non working password) that has a cache of all of the email until loss of access occurred. So when I do the account recovery form, I have name, DOB, region, past passwords and data for all fields including sent email Id's and send subjects, But every time the MSFT recovery mechanism says "Unfortunately, we have determined that the information provided was not sufficient...". WTF.

Every time I contact MSFT support I get the same answer, an explanation of the point system used to reset the the account. Same steps to recover....based on this, the recovery should work...yet it doesn't. I have tried somewhere 50+ attempts now over the last 9 months. I even have a contact who is VP level at MSFT who sponsored a support ticket internally but that just ended up with the support person sending me a link to the account recovery form and closed the ticket without looking in the details of the ticket.

I can't modify / add a new account as MSFT has as a discontinued product no longer allow members to add/change id's. So I'm locked at the current user set. I have created another email address by saving the cached data to OLM file and importing via the Outlook client but that doesn't restore use of the @mydomain.com for that person. I even retained a lawyer who send a demand to MSFT legal...but the email address didn't go anywhere so at the point of needing to do this on headed paper/send via snail mail.

Does anyone have any idea how to get through to MSFT explain the recovery tool is broken? I assume there are so few accounts using custom domains pin family plans that they simply don't test this recovery path.

At this point without some internal guidance is a) lawyer and force a demand for password reset b) give up, ditch all of the users using the custom domain, configure an alias for all of the accounts and then change my MX record to a company doing email forwarding and then forward to the new/old legacy accounts (i.e. the ones with the mailto:email address removed for privacy reasons).