Mangled email address (on Microsoft's side, not ours)

Ok awhile back when our company was using both Google products and Microsoft products, I already had a Google account and was told that I could use both my Microsoft account and my Google account for work (back when both companies integrated their services seamlessly). So, in order to login to both accounts simultaneously I set my default email account to my Google Account and since then everythins worked. Up until recently. Since where I live happens to be now near a Microsoft Data Center, our company recently decided to switch entirely to Microsoft products. Well, since we are now using multi-factor (as in more than dual factor) authorization I have been having issues logging into my work account. I was told by my IT Administrator that since Microsoft mangled my original (Hotmail) email account when I made my Google (Gmail) email account my primary, is has been the source of the issues with our multi-factored proxy / VPN (my IT admins words not mine). I tried contacting and talking directly to Microsoft support and was told that I needed to create a new email account (which I will not do because I have years of work related documents associated both with my Microsoft and Google accounts) because Microsoft is unwilling to go back and fix THEIR MISTAKE. I see no security reason why I cannot switch my primary email account from Google back to Microsoft (so that I can properly unlink my Google account without losing information from either account).