Cancelled service yet im still being debited everymonth

I called in to cancel my service in March as i was moving homes, I was not debited in April and have been Debited R895 every month since then, When i called to enquire the agent acknowledged the fault and said she would rectify it. I have been mailing this agent with no feedback and i was debited again for july after being told that the issue has been resolved and that i would be refunded