Account cancellation nightmare!

In 2013 I entered into a 2 year data contract with Telkom while I resided in Johannesburg. In 2015 I renewed the data contract however later that same year I relocated to another town where there was no signal or telkom towers. I kept on paying my account monthly for the next 2 years until 2017 even though I did not use any data thereof anymore. In May 2017 I contacted telkom and notified them that the contract has come to an end and they must close it. This is where my real nightmare started. Since May 2017 telkom refused to cancel my contract and kept on debiting my account monthly until now one and a half year later in Aug 2018. Even after numerous calls to their callcentre and numerous emails later to cancel the contract they still debit my account. To add insult to injury I have not used a single bit of data from them since 2015 on this account even though I paid it. I have resorted to reversing the debit orders but they keep debiting and adding interest to my account. !!!TELKOM - STOP DEBITING MY ACCOUNT!!!