This site deals in stolen keys and constantly screws over game devs. They also charge you for protection for stolen cards even though the onus is on them to make sure the keys are not stolen. For the sake of a couple of pounds you could end up with a game code that gets revoked. Do not buy from these guys.
Sounds fairly typical with G2A - a place to stay well away from, really.
I bought this game from G2A once, after a couple of days GOG deleted the game from my account and told me it was a key bought with a stolen card, got my money back from G2A but only because I used G2A shield, so keep that ticked because you never know