I'm currently battling two situations like this: one where I'm waiting for a specific medical appointment which has to be by the end of next week at the latest. I put in the request for it on September 19th (actually, I put it in before that but they lost my details the first time) and they keep telling me I'll get the appt "any day now". Which is fine, except that this means I'm going to have to drop everything at work at very short notice to attend this appointment, which is a nuisance.
The second has to do with a week's holiday I am owed from work. I originally had the time booked off for the last week of October, but now with project schedules changing it looks like that won't be possible. Well, that's OK, I'm happy to be flexible because we haven't yet booked anywhere to go away or anything like that, so in one sense I don't mind when the actual week ends up being. But now my project manager tells me that it will probably have to be the end of November, but he can't be any more definite than that until much much much nearer the time! This is irritating, because if we do decide to go away somewhere for the week then we need to make the relevant arrangements in plenty of time. Why shouldn't I be able to say "Look, I'm taking my holiday from X to Y dates and I'm giving you plenty of notice, deal with it!"?