Still debiting my account - 4 months after cancel

Here once again. My last post was in Nov 2015. I sent a letter in Sept 2015 to cancel my 3G (which btw was last used in Jan 2015) due to poor service. After repeatedly trying your call centre and lack of email responses, a Kabelo assisted and informed the account was cancelled.<br> Please advise why you continue to debit my account & ***** from me - perhaps to contribute to your Nigeria fine? I am no longer a customer, yet you make dealing with you excruciating painful! I am convinced you have a bunch of people with the brain of a 10 year old working at MTN. These payments + interest MUST be reversed today & a senior CS manager to call me with an explanation and guarantee this is the last!!