Yes, poster needs to talk with a lawyer. Ideally, a company would do this on Day One of the situation.
And keep all the data you can (from Web, marketing, ads, etc.), to try to figure out and show how much this is costing you. "And here's where the hockey stick snapped in half."
Of course. As an outside party, you're not bound by Microsoft's EULA. You can go after them for defamation, tortuous interference with contract, etc. You're in a much better legal position than a customer.
This is when you have a lawyer send a letter. That's cheap. That gets your lawyer talking to Microsoft's lawyers. Most commercial disputes are, in practice, resolved that way.
And keep all the data you can (from Web, marketing, ads, etc.), to try to figure out and show how much this is costing you. "And here's where the hockey stick snapped in half."