(no subject)

There's nothing worse than someone who has to have the last word. And unfortunately I'm dealing with one of those at the moment. Grrrr. Let's call him Q, though that's not his name...

A situation arises in which I have to have a discussion with Q about what should happen next - sadly the majority of the following is via passive-aggressive email or secondhand through another team member:

Q: You need to do Y.
Me: Okay. *looks at policy, in which there is no mention of Y* Hmm. *phones Q's admin* Can you tell me about Y? Is there a criteria, a policy or anything that actually tells me about it?
Q's admin: Dunno. What's Y?
Me: Okay then. *looks again at policy and decides to do X*
Q: You need to do Y.
Me: Y does not appear to exist any more. If I can ever find out what Y is, assuming it's not a duplication of something I've already done, I will do it.
Q: You need to do Y, which is in fact X under another name that nobody has referred to it by for nearly 5 years, though I have failed to mention this fact in any previous conversation but will subsequently claim I have. In fact, you should have done it 2 or 3 weeks ago.
Me: *headdesks repeatedly*

I am so hacked off right now there are barely words. Any tips on how to handle passive-aggressive dipsticks like this gratefully considered!