I would suggest that, for now, you do not make any further Bids. Just patiently wait until a minute or two before the Trade Expiry time- then Bid .(As in Poker, do not unnecessarily show your hand early)  A 'confederate' (if there is any) may, seeing no further bidding interest, be lulled into thinking that their conspiratorial arrangement has worked and is therefore unlikely to sit around to scrutinise those last two minutes. Marty.