Byju's: The unravelling of India's most valued startup
bbc.com
bbc.com
* the courseware later turned out to be material freely available online
* the actual attention paid to individual students in these courses was minimal -- once they had your money, you (more precisely, your child) were ignore.
* they made people pay a lumpsum -- so you could not cancel after (say) a couple of months.
They also actively (and fairly successfully) suppressed complaints on social media. I'm not sure how they managed this at scale.
Their underhanded tactics were eventually too much even for their own employees to stomach, which culminated in this "Feedback letter from employee to Founders, CEO, and CTO":
https://www.reddit.com/r/developersIndia/comments/14h0mm6/fe...