Have you considered that your service, unbeknownst to you, may have been compromised at some point in time, and the source of some phishing page or other malicious material? Besides that possibility, if your business is truly being "destroyed," have you contemplated retaining counsel to escalate things with Microsoft?
Does it hurt Microsoft in any way to answer those tickets with "no, your site is participating in a phishing campaign"? And maybe tell the OP how, so that he can clean the malicious material? And yes, that is a major defamation campaign led by Microsoft against the OP. And since MS even refuses to clarify their claim about the OP's wrongdoing, I imagine he would have an easy time in a court.
Ye, it tells bad actors how the detection system works.