closing an account can't be so difficult

I closed my account with cape union in March, sent through an email with the proof of payment. Theresa in phoned them to make sure I paid the right amount. Come April I get an account to say I'm in arrears. So I go in again. On the phone for about an hour and they say they'll have it sorted and misplaced the payment. Come may I get an account again with outstanding fees. This is ridiculous. At the shop again to see if they can close it this time.