Attention all passengers: If you have any airline vouchers stored away somewhere, don’t try to sell them. If you do, the issuing carrier might be using high-tech security systems to catch you. The result? The airline will deem your vouchers stolen or invalid, and that will leave you with nothing.
But what if someone else tried to sell your airline vouchers without your knowledge? “You better not try to sell your airline vouchers. This is why”