Which part of close my account don’t you understand!?

I decided to close my Discovery Credit Card due to an exorbitant interest rate that could be compared to loan shark rates. I was able pay it off and now find that Discovery Bank is frustrating my efforts to close my account. I suspect there is legislation that could protect me here. I made one phone call and was told the paperwork would be emailed to me. It was not. Instead there was another phone call during business hours which I had to return on my own time. Just close my ****** account!