Welcome to the world of politics!
Because that's all the whole mess is. The MIS head likely knows for a fact that you'll graduate before getting wireless. Simple truth. She just can't say it. Again, for political reasons. If you keep giving vague hits and suggestions that things MIGHT get done, then you never have to deal with actual answering questions from those on the other end as to why they're not done. Sure, it would have been easier to either give you the figures you wanted or tell you she hasn't a clue as to when it'd happen, rather than go through all the beaureucratic red tape she did. But doing so would have jepordized her position because you'd suddenly have a fact on which to work with.
As for what you said to her and the way you said it, while it may be blunt truth, you have to remember that she has position, and people in position cannot stand to be talked down to. Her reaction was exactly "You're a student. Who are you to be demanding answers of me?" The more beaureucratic the environment, the more this is true. So, you have to play politics and always remember your place as a peon, as a being below her station in life. If you play that well enough, higher ups like that may deign to actually heed your requests. Attitude like yours could only be given to those lower down in the political heirachy than yourself. Attempting to give it to those above will only result in smiting for impudence, no matter how correct or factual whatever you're trying to express may be.
Really, the moral of this whole story is "know your place, never step out of it, or of you do you'll be stepped on."