Account not closed as requested

I requested for my account to be closed on the 26.09.17 and was advised it will be closed after the 12.10.17 but when I asked for a confirmation of closure I was told it had a credit balance and they cannot close it yet no communication was made to inform me prior to me asking them now they say it will be close after the 12 in November and that is totally unacceptable ,I want it closed as in yesterday because it they communicated this credit balance before I would have told them to write it off then