Question about account reinstatement when you can’t access the account

Short version, theres this phantom Amazon account causing suspensions for my MX and CA marketplaces. This account was opened 4 years ago by a former employee (who has since passed away) and until recently, we were unaware the account existed. I need to reinstate this account to lift my suspensions, but I have no clue how to access it. We’ve tried every possible email address and even if we had that, we still wouldn’t know the password. Seller support has been no help, saying that I need the email address, even with our business owner on the phone and this account having been opened on behalf of our business, no luck.

Any ideas? Thanks in advance.