Has this just happened? If so, wait a day perhaps then send them a message via the contact option (there must be one, perhaps at the bottom of the page).
I logged on one day and had three messages waiting for me. One to say I'd violated rules and as a result banned, then two more saying the ban had been lifted. It was obviously some mistake. The usual rules apply (not posting re things that are illegal). Where I was once caught out was posting on the wrong wall (although I received a warning rather than a ban, then I immediately replied to apologise and explain I must have posted on the wrong site accidentall). Part of the same group is extremepigs.com and chempigs.com (not sure if there are others).