Well funny story with CEX, I went to one in Northampton to trade in some stuff for voucher or to get 4k version of Ready player one on blu ray.
They had a Ready player one 4k on their shelf, gone through trade and had to pay additional £1.
Poor guy was probably new, he did all the exchange and payment before checking if they had stock.
Turned out the disc got damaged or something so they couldn't sell me it, gone a long process to refund me £1 and change my exchange to a voucher.
While they were doing that, a customer next to me bought 2 copies of MW2 for Xbox one X from Milton keynes CEX.
Turned out the cashier person gave him 2 copies of MW1