If internet is that important for your business why are you using a residential grade broadband service or at least have services on redundant delivery mediums (e.g. one DSL and one mobile broadband)?
I know many people/small busineses do, because they have got a 'home business' connection, which is basically a residential line but being marketed for business. But people doing that should at least have a mobile data backup to use for important emails etc, even with a full busioness connection in an office. I can confirm it went down about 1am this morning as I was working late and that is about when it stopped working. My concern is why it took them so long to be alerted of the problem, they are one of NZs biggest companies, so I would have thought they would have 24x7 monitoring, and real time status updates on their website, especially for major and widespread outages like this.