Some years back I moved to a different city. About a year later I wanted to make a purchase with my credit card. I found out it had expired. I rang the bank and asked for a new one. They promised to send it to me. It never arrived. Rang again, got the same promise, and still no card. When I called them the third time, the employee found out my old address was still in their database. Turns out the credit card department had a different client database then the debit card department (who had my new address).
To change my address, I had to log in to their site. They weren't allowed to change it on the phone. As soon I tried to log in, I noticed I forgot my password. When I clicked 'reset password', there was a new surprise: they send the new password by snail mail.... to the old address of course!
So I had to go in person to the house I used to live in and explain the situation. I asked them to ring me when the letter with my name on it arrived on their doorstep. Luckily the people who now live in my old house were very nice and gave me the letter!