Line cancelled but still being billed

I have cancelled a line in October 2017 and to date I am still being billed and now seen as in arrears. According to Vodacom's records the line has been cancelled, can someone fix this as the call centre is useless, you are sent from one department to the next who cannot assist.

I have been struggling with both my lines I have with Vodacom since July 2017, I cannot wait until my last contract ends this year. The service is appalling!!!