A few days ago I obtained a full refund on a pair of tickets that I'd purchased from the ticket office at Paddington earlier that day (the reasons that I couldn't use the tickets are not relevant here). In the morning, I paid for the tickets with a credit card. In the afternoon when I handed the tickets back for the refund I expected to insert my card into the reader to re-supply the details. I was slightly surprised that the fare was refunded to my card (yes, I was given a receipt!) without me providing any card details - which implies that the GWR booking system had kept a record of those details. When I use a card for any purchase on the internet I'm normally careful to leave the "remember card details" tick-box unchecked as I don't particularly want those details stored on a server somewhere "in the cloud". Does the GWR (or any) back-end system keep credit-card details indefinitely? Is there a way to remove those details?