The tragedy of the commons...
...look it up.
In the early days of the web I used a London based web host for my client web sites. They had a policy of unlimited usage.
It was fine for many months but then it started to get slower and, within a few days, glacial. I established the cause. Another user was hosting a single page web site which appeared to be promoting an islamic religious book, there were no internal links from that page but there were other pages, a substantial stash of pornographic images, available to anyone who knew what page name to enter to the browser.
The news of that stash had spread. One the technicians they employed was not happy with the situation and went public with the bandwidth usage stats on a user forum. About 95% of the total available bandwidth was being consumed by that one customer. The management response was to put the blame on the lead time for getting additional capacity. What surprised me most was that many users on the forum who were all suffering the same virtually unusable speeds supported the management's stance of unlimited everything rather than apply some kind of fair-use cap.
I spent an entire easter weekend shifting all my websites elsewhere, mostly early morning when the porno enthusiasts had worn themselves out.
I think it's common for ISP and hosting contracts to include constraints such as a "fair use" clause. I believe my "unlimited" fibre broadband provider has a policy of throttling usage if I were to exceed a daily threshold, reinstating normal service at midnight.
If SK Broadband are having a problem and have some kind of fair use clause they should be invoking it, if not they need to amend their contracts, hike their monthly fees, charge a premium to Netflix users, block or throttle Netflix pending a resolution.
Fundamentally it is a mistake to set up any kind of "commons", in the case of internet services advertising unlimited bandwidth, disk, websites etc. It is a fiction, it is not deliverable and will be exploited by someone.