Just checked with my brother who works at CSL - they legally can't use the term "Unlimited Data" because of some telecommunication law.
If you have 4 people to share your family plan then this is what I am using:
https://www.hkcsl.com/en/new-multi-user-service-plan/
You will need to have a minimum of 10Gb + 10Gb for $588 + $108 (capacity data plan aka unlimited data) + 18 (gov't Charges) = $714
Now if you are 4 people sharing: 714/4= $178.5 per person.
In our plan, we have people who go crazy with their data use, +150GB per month of data use and streaming. We recently renewed for another 2 years.
Let me know if you want to sign up, can refer to my brother.