Vodacom *****ing after cancellation of contract

If I could rate in minuses I would. I cancelled my contract 6 months ago as we immigrated and Vodacom is still debiting my account. I have not upgraded my phone hence I have no ‘balance’ to settle with them. I have sent emails, phoned over and over again. Effectively Vodacom is now *****ing my money. I do not know what to do anymore just for a simple cancellation to be processed. I will not advise anyone to ever deal with Vodacom as this is a life long contract you simply cannot get out of. I am so frustrated.