Unable to close account

I have a RCS card which has been paid up for the last year +<br> I have made several phone calls, each time getting the same answer. Send your ID and letter stating you want to close the account.<br> I have sent this info 4 times over the course of 7 months. I do not get time to follow up on this every day, but now I am fed up.<br> Each time I phone them to complain accounts department are either closed or some random excuse.<br> I just want to close my account and stop the constant sms's and emails I am receiving.