Two-factor authentication methods used on my account are no longer accessible and I can't sign in

Dropbox Plan
Unsure

Are you a Team Member or Admin?
Admin

Do you have access to the email linked to the account?
Yes

Question or Issue
AT A CROSSROADS with Logging Into My Account.

I have been a Dropbox accountholder for over a decade. I have never had an issue logging into my account up until now. I originally established my Dropbox account to store important life artifacts, like old photos of our family, etc. And, thus from time to time over the years when I had the space in a busy life to log in I would update what I wanted to continue to add to the story of our life's treasures.

I have been attempting to log into my account over the past week with no success because the two-factor authentication methods are no longer accessible to me. The devices on file are no longer owned. The phone number on my account's file I no longer have access to (my employer issued me that number and I no longer work there). And, the backup codes it is suggesting I access I do not have. I have been going back-and-forth with email support for days now and my experience is the email support team is not comprehending this and keeps repeating their support recommendations, thus I am finding myself repeating the situation now 3 times. I am no closer to getting help with a manual account recovery option. I even offered to provide additional account verification identification. I really need additional escalation and help with this matter. 

I respect the role in protecting our data. Equally, I am having a difficult time respecting the support experience for a long-standing customer who has spent hours attempting to get adequate assistance that resolves an issue, versus perpetuating the inability to use a service I have invested years into, and I am still currently paying for.

Below is the screenshot showing the devices linked to my account that DropBox has on record for me. You will find these haven't been active in the past 5 - 8 years.