Worst telephonic service for credit card closure

Struggling to close my credit card with this bank. It’s been over 2 weeks calling for them to send a settlement letter but nothing. I then paid the outstanding amount a week ago after consulting the bank branch due to no proper response on the phone and I was told I can settle then call for closure. I call these people almost every day to close this account but nothing happens. Even owning a bank account with them was the worst nightmare ever, I had to close it and that still took weeks to close. What is so difficult?