>The weirdest is that some ISP are blocking it and some are not. So why is that the case? Are some ISP not listening to the government?

Pretty much. My ISP doesn't block half the stuff the Indian government has banned, while my mobile data provider has - it's genuinely very weird.

Regarding contacting the government - maybe https://pgportal.gov.in should help? File your grievance with the section of the government you want to complain to - in this case, I'd guess that's the Ministry of Electronics and Information Technology.