OK, so it's a permanent facility. Well that's a bit easier. Assuming this is a bar on campus run on behalf of the college, the organisers should be taking it to the college management, and pointing out that what the bar was doing was illegal and should not be allowed happen again. There could even be a legal liability issue for the college if it runs the bar directly (though I assume it contracts it out to another catering firm).
If you're talking about a completely independent bar, open to the public, then either write to them formally or go directly to the National Consumer Agency.