I'm surprised that it didn't say why but the typical reasons are boosting, glitching or offensive emblem. You can try contacting Activision Support but I think that all they can tell you is that you are banned but not the reason for it. 3arch does the banning as far as I know and no one that I'm aware of knows of a contact point within 3arch for discussing it. What I can tell you is that if you've been found guilty of boosting or glitching you can expect to received a full reset once your suspension is lifted. That seems to be the trend. However, I obviously have no insight whatsoever into your particular situation.
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