Could be... This is found on isky.co.nz:

To improve the quality of iSKY's video streaming, we're upgrading to a new content delivery network (CDN) later in June. This will result in faster and improved reliability in delivery of content for iSKY users right across New Zealand.

When this upgrade occurs, our Broadband Partners will no longer offer unmetered iSKY data plans. This means that iSKY usage will be counted as and be subject to your data plan. As heavy users of home broadband and iSKY ourselves, we are confident the change will be worthwhile. In fact, this may not impact your data plan as much as you expect.

We have provided more information in our frequently asked questions below.