Hey, I'm really sorry to hear that you have been experiencing issues like these with someone in the community. When an incident like this occurs that breaks the Code of Conduct, the first thing you should do is immediately file a complaint. If you feel that the user is going to continue to bother you you can mute the player which will eliminate them from contacting you further. To learn more about how to file a complaint, as well as how to mute a player, please refer to this article support.xbox.com/.../chat-terms-of-use-conduct . If you feel threatened or at risk of being harmed in anyway by the offender, remember to never hesitate to contact your local law enforcement agentcies.
Once again, I am very sorry about the experience you have been having and I hope this helps resolve your situation, to get you back to having fun in the community.
Have a nice day,
<IMPOSSIBLE IS NOTHING>
You as the primary person can change your child's privacy settings to friends only and this will avoid communications from unwanted people and as long as you don't chat with them after you can mute them
If your having that many problems then you need better safety for your accounts. I had problems with my kids at first but after a while everything started to work out. I would suggest you look at these links. Both of which are very helpful.
Harassment, filing a complaint, and managing communication
Parent’s Guide to Xbox Live Online Gaming