My wife got a card card for my business and put me as an additional user. For years, I signed on my account and paid the card off in full. What I didn’t know is the “annual fee” appeared on her car but didn’t show on my account because it was charged to her card that she never used. One month, a random paper bill arrived in the mail. I thought it was strange as I was enrolled paperless, I opened the statement to find I had a bablance of over $3,000!! This was from a few years interest of the annual fees!! 😀 Amex gave me no relief 🥲