My suggestion would be to go to the microsoft store app, click "talk to an expert" and as soon as a chat bot opens up just type "real agent" or "real person". Rather than listen to them blather on, simply state what the game files did, how they duplicated, how much space they are taking up, and how you feel.
And just basically say that dudes response doesn't mean anything, and their actions do, but in a nice way. Basically "I don't need to hear anything, my respect/future purchases will be decided based upon the actions taken by the respective companies to solve this issue".
The guy i spoke to was very understanding and eager to hear what I had to say. I doubt anything will be done but its worth the 5 minutes; And threatening company pockets is pretty much the path to success in 2020 cause respect doesn't mean much. You can't really appeal to your needs and expect them to do anything; Rather you have to threaten their future business. You may think it doesn't add up but they'll realize when 100 people are messaging them with this and "threatening" to forward the information, they take notice.
This is very bad PR for both companies. So if you like you can also contact games journalism companies. Most of them likely won't post negative articles just to help gamers, but its worth a shot.
Microsoft is the company with a face and name here, and Microsoft has much more stake in the game, with much less to gain out of the deal. They'll be the first to act, if anyone.
I'll be forwarding this so just ignore it if you see it in other threads.