complained about the level of bullying at work....
was told "Well we did bring it up at the interview"

FFS! if someone's behaviour is so bad that potential new members of staff have to be warned should they not get rid of them?
(Lip Up Fatty Fatty Reggae still loves BBQ food on, Thu 2 Sep 2010, 20:54, 3 replies)

I'm pretty sure
that, legally, telling you about it indicates that they knew about it, which makes them if anything more liable, not less.
(apeloverage committed the vile act of onanism on, Fri 3 Sep 2010, 2:31, closed)

Certainly does
Having just sat through a management course I can tell you yes that makes your company more liable, not less.
And whoever "warned" you is an idiot because they've just made themselves the target of any compensation claim.
Not sure what country you're in, but here in Australia, bullying in the workplace is against the law, bosses have a duty of care to make sure it doesn't happen and if it does, the bully, their manager (if they take no or inappropriate action) and the company in general can be sued to the shithouse and back.
Here's my advice:
Keep a diary from now on of every incident including times, dates, what happened, who was there to either be a part of it or witness it.
Keep notes of when you raised it with management and how they reacted, keep every email or communication that is bullying or even slightly dodgy (if you have a conversation with someone that turns bad, email them straight away saying you're not comfortable with what just happened and don't feel it was appropriate or just that you'd like clarification and KEEP THEIR RESPONSE.) Yes you might cop some flack for the email but it's the response you want because...
Once you've got a couple of months worth of good examples, you go to your company's HR person and hit them with the lot at which point one of two things will happen.
A) The bully will be fired on the spot or
B) They'll try to make it sound like it's your problem or
C) They'll do nothing again.
If either of the latter two happen contact a workplace relations lawyer and watch them wet their pants in delight at what's about to happen.
They'll sue, you'll get a wad of cash, the bully will be fired.
( difficultchild, Fri 3 Sep 2010, 6:02, closed)

And if you "get flak" for complaining about or highlighting the bullying
that's also an offence, here in the UK at least: victimisation.
(moon monkey is busy making memories worth repressing, Fri 3 Sep 2010, 10:44, closed)