Shared resources and blacklisting is a common problem in Cyber Sec. If a company blocks a malicious IP, it could be an ISP NAT for hundreds or thousands of people. Similar issue is happening here where your higher level domain is getting flagged by the fake pages using registered sub-domains.
Here is the thing, the false pages are ultimately your companies responsibility. If your company can monitor for scam pages and prevent them from going up in the first place, ultimately the domain blocks should go away. Many of these are on a 30 day cycle (although I can't say for sure, it's company based). Can you not just have a review of each new page every day? I'm not sure how many new landing pages are being created here. You could definitely script something to pull all of your DNS and run it through a URL checking tool and send you alerts if something flags. That would at least get you closer to being ahead of the curve.
Frankly, the websites should be blocking your domain as long as you are hosting malicious Phishing landing pages (or etc). That's what that mechanism is for; to protect people from exactly that.