Your download mirrors for Australia seem to come from Japan which, while geographically sort-of close-ish, has, frankly, terrible connectivity to Australia. For example, I typically get from 1 to 4 kb/s. Atm I am downloading Krita-4.0.0beta1. I get 1.3 kilobytes per second. This is not the first time this has happened. Could you at the very least provide a way to manually select a mirror to use.
So, that download failed with 2.7M received. For comparison I got the full ftp address from firefox then used it to navigate the UK Mirror service and download from there. I am getting 110-190 kb/s now. My download time has gone from 6 hours to 6 minutes.
You're seeing this issue because as noted at http://ftp.kddlabs.co.jp/ that mirror is currently under heavy load. If you browse the download server you'll notice "Details" links on each line. This will take you to a list of mirrors and offer other options to you as well such as Metalink files, along with the hashes of the files. Note that you can also append ".mirrorlist" to file download links from either download.kde.org or files.kde.org and the same page will be presented. The only proper solution to this issue is for a mirror of download.kde.org and files.kde.org to be setup in the South Pacific region.