It seems like some credit card companies do not want to know about phishing scams targeting their customers. I tried to let Discover Card know about a scam running at discovercard-service.com (which is NOT a legitimate site; it is run by fraudsters) but they did not seem to want to talk to me if I was not a customer of theirs. And I could not easily find any place on the real Discover Card site to make a report.
Frustrating.