The IB offers vary a LOT, even for the same subject or same college. My offer was 38 points with 776 in specified HL subjects - but I haven't met anyone else with that low an offer yet, and I've talked to lots of international students -; a schoolmate of mine got an offer from another college for the same subject (chemistry @ Oxford) of 40 points excluding bonus points, with 77 in specified HL subjects. Then again, someone in my college got an offer of 42 points with 77 in specified HL subjects.
On the other hand another schoolmate of mine got an offer (Physical NatSci @ Cambridge) of 40 points and 777 in a choice of four subjects, and another one (Maths @ Cambridge) got an offer of 777 in a choice of four subjects (+STEP), but no overall score. (Or at least it was something to that effect, I don't remember exactly any more.)
So the offers for the IB do seem to vary a lot more than the standard AAA offer which it seems everyone with A-levels seems to have got, and the colleges are right to tell you that it depends on lots of factors (though their precise nature seems to be quite indiscernible and mysterious).
Which college and subject are you thinking of applying to?