I think your throttling is probably unrelated to the fact that you have exceeded 30GBytes. I have only downloaded about 15G this month, its 23:55 and I can't get more that 20k on massively seeded torrents, and this on a 4M line. I am using a pure IS account (not an ISP that resells) and during the day P2P stuff never exceeds 8k.
My overall experience is that HTTP, POP3 is good all day, FTP intermittent, NNTP very bad during the day and P2P very bad all the time. All in all I would say that if you want to do anything more than straight forward browsing and mail you should look elsewhere, which would make the idea of purchasing an uncapped account somewhat unusual, unless you possibly purchased an account with a seedbox company, but the good ones (should I say reputable ones) are usually charged out in Dollar's/Euro's and once you combine that charge with what you are paying the ISP, well I am not so sure its a big saving on the larger capped (semi-shaped) accounts.
One of my companies actually re-sells IS connections, in a small way as part of a total web solution as we are in the business of writing desktop software solutions integrating to online databases which in turn drive websites. In light of the performance in certain areas we feel it important to tell prospective clients that the IS uncapped option does not make any real sense if they have a significant non HTTP/POP3/SMTP component to their normal daily business. I suspect all resellers should do the same, but reading through the forums its pretty clear they do not and in their defence most resellers are not really given too much information from the companies they represent, we certainly are not.
Interestingly as I have been typing this reply, we have moved past 24:00 and I see that the same torrent that was running ar 15k-20k has just been "bumped" to 300k-350k, almost exactly at the stroke of midnight. So there you go, these accounts are great for general browsing/mail, but if you want to do a lot of downloading but either schedule them to start at midnight or change your sleep patterns!