Very wise advice, carry multiple cards. Some years ago I flew from the Middle East to the USA. During the station stop in Heathrow, I went ashore and made a phone call using my MasterCard. Later when I checked in at the hotel in Miami the card was declined. I could not understand that - it was fine just a few hours ago. Having previously learned the lesson to carry multiple cards, I used another card to check in then phoned MasterCard. They verified that it was me, that I still had the card with me and turned the card back on. It turns out that card thieves test the card by making a phone call to see if it is still valid. If it had been reported stolen and cancelled and they tried to use it in a store, the store would call the cops.