I had a similar, but far more disturbing, situation at our last flat. When we moved in, there was a lovely couple above us. Then the drug dealers moved in. One of them also regularly beat his girlfriend to within an inch of her life. The walls were thick, but it would still wake up the entire building.
Fast forward to last Easter Monday. After months of complaints to the police, council, and anyone who would listen, they took it to a new level. Somebody had graffiti'd their outside doorbell, and they decided to kick in every door in the building. We had a ground floor flat, and they knew we knew what was going on (mostly because over half the customers would knock on our window to ask for access to the building). As a result, they also smashed in the glass double doors that were between our back garden and our bedroom. Had we not planned ahead and fled (in my case, barefoot) down the back alley and to a local hotel where we called 999, we're guessing we might be dead or as good as right now.
Hopefully you'll have better luck pursuing legal action, and it seems like you're just dealing with semi-normal university student cockiness (as opposed to career criminals, dealers, and thugs).
Anyway... is the building all owned or managed by the same person/company? Is their lease specifically dependant on their status as students? Do you have a direct number for the Community Support Officer that works your area? Do you have a decibel meter? Are you keeping detailed records of everything they're doing?
The dB meter is good for keeping track/records, and they only cost about £15.
Keep in mind, though, that these kids are at the age where they think they're invincible. They'll keep harassing you, perhaps even after (and if) they get evicted. It might not be worth the fight in the long run. It might be worth talking to your agent and demanding that they move you. (If the kids were there when they showed you the flat, and they knew it was a noisy place, and they didn't say anything, they'll likely find you a new place instead of facing a court case involving false advertising and not providing appropriate housing, etc.).
Good luck!