Cancelling Overdraft facility FNB, nearly impossible

Getting an overdraft facility is very easy with FNB as private client, CANCELLING it nearly impossible

The overdraft has been paid in full and the cheques account is sitting in positive balance, we simple wanted urgently to remove the facility so that we don't use it. Left a complaint with FNB Complaints ref *** to be told it takes up to 48 hr to get a response.