I bought a Khaki jacket I spotted when I was window shopping before.
It was the same shop assistant who served me last time and she remembered me. When I was at the till, I was asked to write my address down for direct mailing then I said 'By the way, I've received a postcard'. The staff said 'You should have mentioned such things much earlier,. shouldn't you?' cancelling the credit card payment and re-do it at the discounted price. I felt the way she talked to me was a bit arrogant, but she quickly sorted it out saying 'Always better to pay less', without making me wait.