Thanks again everyone!
Good idea NyaChan, I will set up the read receipt function, at least I will know who read my email and who to follow up (for instances when I am obliged use a generic email acct, I mean).
Thanks Bopper and Decimus, yes I think that's what it will amount to. I agree Rashea that they are probably overwhelmed with work, so I don't take it personally.
Deetee I don't think its impolite, and in fact I do have to stop myself from being impolite when after several requests, I get no response. I would love to do the written equivalent of jumping up and down, demanding answers and well, throwing a tantrum - but no, not a good idea
I guess I really feel powerless in this situation because they can choose to ignore the requests and there are no consequences.
I know my descriptions are probably a bit vague, but think in terms of a help desk - you usually can't go visit them and meet face to face, you shouldn't have to really negotiate what you want, you just want help which they are supposed to provide and you shouldn't have to continually request and wait and wait and wait.
Thanks for all the suggestions, I know I will be able to put some of them to good use!
<edited for grammar>