Oh okay...is there anything I can do? Should I go and get put on the general waiting list? Also, for the waiting list how does it work? Do I get "locked" into a random college's waiting list or can I actually choose the colleges I wish to apply to like the first time?
Check out and carefully consider Salmond before the waiting list. The general waiting list is the list that people waiting for spots go onto, and is generalized - everyone waiting for a spot is on there, and whichever college has space takes people from it. There is no choice or preference, you simply go onto it, and there's no telling who could give you an offer.
Although you'll hear stories of people getting into popular colleges off the GWL, they are the exceptions, not the trend.
As usual, we don't advise turning down what you're offered unless there's a very good reason - and simply saying "oh this one doesn't look as good" is not one. You're likely to end up in colleges considered 'rowdy' via the GWL, and if you ask me I'd say you could be doing much worse than Salmond. Also, if you're really unlucky on the GWL you may end up without an offer at all, meaning you'll have to come down to Dunedin and try to sort out some sort of flatting arrangement, which I'm pretty sure is much more stressful than being at a not-as-popular-as-StMargs college.
I don't know how many times this has come up in this thread, but turning down an offer because you wanted a "better" college is NEVER a good idea. At its core a college provides you with warm shelter, regular cooked meals of reasonable quality*, and a bunch of other freshers to make friends with; NEVER underestimate the importance of these three things, and don't overestimate the importance of other things.
In short, if you go on the general waiting list, you do so at your peril - your chances at getting a "better" offer is tiny, and you're not guaranteed an offer at all.
*: I believe meals are extra at Toroa?