who to call for housing issues?

[borgin.livejournal.com]

I'm sure that this has come up before but it might be worth having a newer post. I live in a building that is experiencing some leaking issues, and I'm not sure who to call in the city if we can't get anywhere with our landlord about this (while having him fix the issue without a third party would be preferable, I'm not sure that he would do it). It seems to be a problem that is affecting multiple tenants.

Thank you!