Thought this was worth sharing, normally when I buy from amazon I use no rush delivery to get the promotional credit. I emailed Amazon yesterday asking how much I had to be told £134.
Not believing this I asked again for confirmation and was told £134 to spend on Amazon products (but not kindle).
So I pre ordered the PS4 Pro and saw no promotional credit applied. After a 10 min conversation with Amazon they have agreed to refund me £125 on dispatch and I have £9 promotional credit for kindle books.
Even Amazon don't quite know where the credit came from.