Do you know that the Visa card you use most often can, without your consent, become an American Express card? This is what happened to many MBNA customers recently, as reported by New York Times.

According to the article, MBNA "invited most of his group's 100,000 members to apply for American Express cards this fall. But it chose about 5 percent of them to switch automatically unless they notified the company that they did not want the new credit cards, known as MBNA Rewards American Express cards."

One month ago, I shared the news that MBNA started to issue Amex card. My judgment was the reward offer in its first product, MBNA Rewards American Express card, was not attractive at all, even compared to MBNA's existing product line.

On the other side of the table, MBNA has all the incentive to push or convert more people to the Amex camp. Why? Amex charges more merchant fee than Visa or Master, so by keeping (or lowering) the rewards, MBNA can get a fatter cut of the pie.

But is it ethical to convert cardholders without explicit consent? MBNA really crossed the line this time. Good for MBNA investors, not good for MBNA customers. MBNA is testing sutomers' loyalty and probably it will see the revenge soon.