Can't seem to get Contract cancelled.

I have cancelled my Cell C Wifi contract in December 2017, payed the cancellation fee called then they confirmed they received the fees payed and still they deduct the money from my account and send me invoices. I have called the retention's office many times and they have all promised to escalate and call me back but this never happens. my last call was to Condi on 01/02/2018 and my ref: ********** ********** 1. and still no feedback.

Their Customer service is terrible to say the least, will never reccomend then to anyone or use their services again.