Poor service: cancellation of old telephone line

We moved offices in September 2015. Immediately arranged for our old telephone line to be terminated as we would have a new telephone line and number. However, the line is not terminated and we still get billed. After numerous attempts of solving this dispute, we get transferred through all departments who advise that we need to send the cancellation form to a certain [Email Removed] or [Email Removed] We have done so indeed. This morning, we contacted Telkom again, enquiring our dispute. The consultant advised that we forward the cancellation form again to the above email addresses, but when attempting to do so, a return mail was sent with the following message: \ The recipient's mailbox is full and can't accept new messages at this stage\". How will this matter be resolved then? Why do we have to pay for a telephone line no longer in use if all our previous attempts to solve this matter sadly delivers to no avail. "