Someone has sent messages on my behalf. I need help

One day while playing For Honor with a friend, some gamer messaged us boasting about killing us.Shortly afterwards messages in the conversation appeared that I never sent. These messages were then reported and got me banned. I tried filing a case review
and long story short the enforcement will not help me because I have a "history" of harassment (I've been suspended one other time over the span of my 6+ years on Xbox live). They said they found no evidence which i find hard to believe since they must have
some way to see what device and where those messages were sent on. Also when i checked my Microsoft account activity i found someone had accessed my account that day from a completely different state than the one I live in. Can someone please get the enforcement
team's attention to actually try and help me with this matter instead of brushing me aside. Just in case anyone was wondering, yes I have changed my password twice since this incident. I would appreciate any and all efforts to help me with this endeavor.

:)

 

If I block someone I've messaged and change my tag, will they be able to see I've changed it?

Someone messaged me over live and my friend replied, turns out they're creeps and when I block them another account tries to add me on their behalf.

If I block them and change my gamertag, will they be able to see on the previous messages that were sent to them that my name has changed?

This is on 360 by the way.

 

Can't access Update Preview forums.

I have sent a message on your behalf. Keep an eye out for a reply confirming access.

 

Submitting a case review is the only way to contact the enforcement team and have them review it again. So if they already upheld their decision, there is nothing else that can be done.