How to lodge a formal complaint to Microsoft/Xbox?

As Owen has already mentioned, the only place to formally lodge a complaint against someone is through your console using the tools offered to you. Whatever Support told you is incorrect. File your complaint, block communications with said user and avoid
them. That is the best advice anyone here can give you.

If you feel you were treated unfairly and they didn't handle your claim correctly you can always file a complaint. Do you still have any of the case #'s or information as to the identification of the person who helped you? (Don't post it here ) Reach back
out to Microsoft and tell them everything as you have here (with the added details I mentioned) and lodge a formal complaint. It's your right if once again you feel you were turned away in error. I really hope this helps as I know how frustrating it can be.

Keep Calm & Game On!

This is a problem Microsoft Support is unwilling to remedy. A complaint has been lodged for investigation by our regulatory authority

Support is about to send me to "tier 3" for the 3rd time in a week. They are supposed to follow up within 24-48 hours, and they have failed to do so twice already. this is bordering on bizarre.

I'm already thinking of returning my console. it is literally a $550 paperweight right now.

Is there any way to lodge a formal complaint or something? This is really getting tiring.

are you trying to report a game that is on the xbox store or something else?. I think we more information to try and assist you with your inquiry