Managed to get the "VG20OFF150" code applied retrospectively to my Xbox One X Scorpio pre-order with Amazon UK, so have £20 off it if I decide to keep it. Makes it £429. If you've pre-ordered with Amazon, it's worth trying your luck with someone on chat.
Lucky, they're refusing to do it for me:
Thank you for staying connected.
I have checked this from my end.
This promotion is valid only for the orders placed after Friday 25 August, 2017.
As this order is placed before that the promotion is not applied.
Me: are you able to do anything for me? I can't cancel it and re-order as it's out of stock
I would really appreciate it
as other people have had success having it retroactively applied to their order
through Amazon chat support
To help you with this I would be able to Issue a promotional credit of £5 to your account.
edit: I haggled them up to £10 off