Citibank Cardholder-Beware your card can be cancelled anytime

Recently I went out for dinner with some business guests and pulled out one of my Citibank credit cards to pay the bill. The waiter came back and said that the card was invalid. I was shocked. For a moment I thought I was in trouble as I didn’t have enough cash with me. Then suddenly I realized that I have another Citibank card, so I gave the same to the waiter. Fortunately the other card worked and I was able to pay the bill otherwise I would have been washing dishes at the restaurant, courtesy Citibank.