unable to close account

Since 2011 I've been trying to close the account every year. Every year I either receive an sms stating I have an outstanding balance or my account is overdue or I have to collect my new card. Last week I called the service number and they could not issue me with a reference number as the system was delayed. To date I still did not receive a reference number. this is unacceptable because every year I need to make several calls and go to the bank to sort this out to no avail.