Can't sign into Microsoft Excel with Apple ID and Apple will not help

I had purchased a Microsoft 365 subscription May 2nd for a year. It worked fine for exactly THREE WEEKS. Suddenly, it was saying I needed to log in to purchase a subscription. I had just paid $99!

Well, thus has ensued hours of headaches and phone calls with both Microsoft and Apple. NEITHER ONE will help. Both say it's the other's problem. And here I sit as the consumer out $99, and really frustrated. One Apple Tech said to charge it back--it's a known issue--another Tech told me no, don't do that, they'll put a lien on your Apple account. Goodness! So, what can be done?

I've tried everything. Uninstalling Microsoft, using the license removal tool, logging out, making sure the app was up to date. When I try to log in, a box comes up that only allows me to use a Microsoft email. Which of course doesn't have the subscription. I purchased it on Apple. Apple denied a refund too which is ridiculous! I told them this doesn't work.