I've had somewhat similar experiences quite a few times. Front-desk staff have trouble switching one VISA card for another -- and the gift cards appear just like VISA cards. I always look carefully at the bill to be absolutely sure that the correct card was charged -- and many times it hasn't! And I keep the card, even after the balance has been reduced to zero.

I also had one occasion a year or so ago where the wrong card was charged. I was able to fix it after the fact, but only because the hotel cooperated.

Bruce