I’ve been trying to regain access to a long dead Dropbox account just to find out what’s in it but it’s got SMS based 2FA turned on and I no longer have that number, and I have no backup codes I can find.

This is fine, but I just can’t stop myself replying to the support guy with “but can you help” because he keeps replying “sure, I’d love to help, you can use any of [list of things I don’t have]” rather than going “nah, sorry mate, you’ve fucked it, it’s gone forever”.