Ask for information regarding these "illicit means", and if the person answering you is "James", keep calm and don't worry if you've been banned for something that is illogical or absurd ; eventually you'll be told what it indeed is about if you're persistent enough.
As for this multiclient issue... A GM, if they have any doubt about the identity of a player, can choose to contact said player and "test" them. While this test apparently is something the GM would decide on the moment, failing it or not replying at all can lead to a temporary ban, as a warning, or even a permanent one if the GM testing you is particularly strict. Supposedly this kind of test only is issued to players moving or having an activity of some sort. You don't risk anything if you are simply AFK.
That and also the fact that some players do send reports about characters in dungeons they shouldn't be able to access, 'weird' behaviour and so on. These won't send a prior warning and won't PM you to ask for clarification.
Also note that nobody from the support staff, should they check your IP, would believe that you indeed are using three computers instead of a simple tool to allow multiclienting.