My website has been blocked in all of Italy. Is there anything I can do?

About two weeks ago I started receiving messages from my paying customers that my cloud storage site (pixeldrain.com) had become unavailable in Italy. The blocking seems to happen at DNS level. Switching to Cloudflare, Quad9 or Google DNS solves the issue. But anyone who is using their ISP's DNS servers is not able to reach the site.

I have been trying to contact Italian ISPs to ask what's going on but all my messages are ignored. I have not received one answer in more than a week time. I have never gotten any e-mails from Italian authorities indicating that I'm doing anything wrong.

I'm not sure where to go from here. Any suggestions?