Locked out of account

I have an account linked to another email address which I am unable to access.

Initially the only issue I had was that I had changed my phone and lost access to the previous authenticator app. I still have the same phone number and email address and am contactable through these channels. I filed a support ticket and received no response for several days. I filed another support ticket and received a response saying: 

[PLEASE READ - ACTION REQUIRED] YOUR TICKET WAS NOT RECORDED

Login with or upgrade to a Paid Box Business/Enterprise account for more support options. Or engage with the Box Community here.

When I try to create a new community post however I am redirected to a screen which says:

Setup Two-Step Verification (1 of 2)

Provide your phone number

However, when I provide my phone number I am again redirected to the same screen. I do not receive any SMS on this number either. As such I can't even create a community post using my other email address and am trying to do so with a fresh account and alternative email address. 

Most recently, about 30 minutes ago, my app logged itself out saying the login had expired. 

I am happy to provide proof of my authenticity, eg my ID, proof that I own the previous email address, or whatever is reasonably necessary to get my account back. I just really need to get back into that account. Please do advise as to next steps.

Thanks in advance.