Protip: lecturers often don't believe this stuff, or sort of ignore it. Team assignments are supposed to be about 'the team', so sometimes they'll brush you off if you're peers don't show.
If this is an issue, and the lecturer tells you it's a team assignment and that's just how it is, then as backup I suggest you either forward on or print your emails to this person. It's evidence of your 'pro-activity' and/or their last-minute crap, and might help you out if it's something critical.