*Stats hat* The crude figure is meaningless. The rate - i.e. complaints per connection - is all that's important, and it says further down the article that the rate is actually declining https://www.theguardian.com/technology/2018/apr/17/nbn-complaints-surged-by-more-than-200-in-second-half-of-2017-report-finds?CMP=share_btn_tw …
If the crude number of complaints DIDN'T go up when more people were using the service, that would be very surprising