Frustrated as heck to close an account

Hi, After struggling for a while - I managed to settle my account. Then I am told they cannot close my account as there is a credit due to me and I need to send them my Id, Proof of account and my marriage certificate.. Sent.. Forward 4 months .. still no payment even after I resent the forms - and to 1stlevelcomplaints .. still no refund.. its not much.. but if i owed them.. all hell would break loose.. What else do I need to do to close the account?