VAC bans are ALWAYS automatically. The Steam page related to this also states that you cannot report any players, even if you have proof ;). Please remember that this game is still in alpha and that the netcode has serious problems (I got over 90kbyte/s download just for DayZ today). I still got horrible desyncs in which the world around me froze. This desyncs can also give the impression of someone hacking: As soon as the desync is gone, all of his movements get down in an unbelievably fast speed, or even instant.
