Ban hammer for 13 days ?

I got banned for 13 days and I dont even know why . I am only a diamond 1 . Can anyone help with this?

The Halo 5 ban thread is worth checking out if you haven’t already - it covers typical bannable offenses and their durations, along with providing a location for ban appeals should you need to post one.
Alternatively the Matchmaking and Ranking Manipulation Bans thread might be what you need to look into.

Please use the ban thread pinned at the top of the forums for any queries on matchmaking bans