The last attempt I even had my report from the relevant CRA in front of me as a cheat-sheet, at their suggestion. They believed I’m me enough to hand me (a version of) my report and let me into my online account with them, but not enough to tell someone else that I’m me. Go figure.
(The trouble, I’m pretty sure, was that both times I encountered two “I have literally no idea what relevance any of the addresses you named have to me” answers and I think they only put one of those in each set. Even reading the sheet I never managed to figure out WTF they were talking about. One I got both times, which I suppose was the one I was supposed to know, didn’t even name a state I had lived or owned property in. But nothing about it on the report, so what do I dispute? Luckily I only needed it for a temporary rental and that ended up working out fine—it’s way easier to buy houses than rent one, I guess, which is pretty weird)