Forza horizon 1

Hello sorry i’am french.

my gamertag was banned on 1 forza horizon, I do not understand I did not cheat.
and contacting microsoft, microsoft says my account is in good standing so I do not understand?

Help me please ?

Your account has been permanently banned from the game for illegally using a Traffic Car (system car) which cannot be purchased and is not Gifted by the developers.

That is a permanent exclusion from the game for violating the Xbox Live Code of Conduct:
"Don’t cheat or tamper. For example, don’t:
Use unauthorized hardware or software
Exploit game vulnerabilities or glitches
Make unauthorized modifications to your account profile or its contents (e.g., tenure, Avatar, game saves, Gamerscore, achievements)
Intentionally play with someone who is using unauthorized software or methods"

You may write the developers at forzafb@microsoft.com if you wish. Neither bans nor the enforcement of the regulations are discussed on these forums.