Fortnite account hacked?

My Fortnite account has apparently been hacked and can no longer log in. Actually had a really tough password and two-factor authentication. I've already written to support, but they say they can't identify me as the owner, even though I've sent various screenshots of invoices, etc. What can I do?

Try again and send more evidence that can legitimize you. For example, address documents (electricity bill, ID card, etc.), account statements with direct debits from Epic Games, email confirmations, telephone numbers etc. Usually help.