Termination request not processed

In May this year I attended at the MTN branch in Pietermarizburg Midlands Mall in order to terminate my cellphone contract. I completed all documents required and submitted the required documents. I did this as I was leaving the country and no longer need the service. I was assured that my cancellation would be processed and that I would be notified via email since I will not be in the country. To my shock my account was debited for a significant amount after I had left the country in respect of services relating to the contract. My request was never processed as per my request. I am in another country paying for a service that I did not receive. I am unable to attend at a branch to request that they terminate the contract, AGAIN!. My calls and emails are never answered!