Sorry for not responding sooner, but your message title misspelled my pseudonym, and I didn't realize you were looking for me.
BotXXXXX XXXXXne would be to file suit in the U.S. Federal Court of Claims for negligence, and then start demanding discovery of all the documents and witnesses that could link the government to its failure to act.
This would be a big project, even for a large law firm. You would never pull it off without professional help. The trick is finding a law firm that would be interested, and on that issue, I can't really give you a clue, other than to say that you need a law firm that has experience suing the federal government.
At the mediation, you could simply describe where you're headed next, if you don't get paid back, and you could mention that you have a law firm lined up (even if you don't).
Whether or not that would give the FDIC attorney something to think about is unknown -- but, it may. You can also request reimbursement based on simple fairness, because the attorney has discretionary authority to reimburse you, even if you're not strictly entitled to coverage due to the timing of the bank failure.
Hope this helps.
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