I would expect them to have some way of verifying, otherwise what's the point in their ticket system having a prepopulated drop-box option for "account recovery" if they're just going to ignore and close out all account recovery tickets without any investigation? I have my original account's mnemonic, knowledge of transaction history, knowledge of when and how much was deposited into the site wallet; yeah it's not absolute proof but it's the best you could ask for. But they're simply not asking.

Unfortunately I never had my GnuPGP private keys saved on persistence via the settings, I've been exporting them manually into a .asc file in the persistence folder, so I can't recover them using what you suggested, thanks for the suggestion though. It's something I'll start doing from now on to avoid this possibility happening again. And yeah they'll be auto-finalising soon enough, I'd just like to be able to finalise so the vendor can get what they're owed sooner