POOR SERVICE

Hello, I have struggling to cancel an account with Telkom. I have signed a contract with Telkom for a WiFi router in November 2017. The problem I have is that Telkom is debiting twice the amount from my account. I have been trying to cancel the other account from Feb 2018 without success. I have been visiting Telkom Kempton shop every second month to complain/cancel the account and nothing has been done to solve e issue. I am always requested to fill out the cancellation forms and told I will receive my money back. They keep sending sms saying the issue has been resolved but continue to *******ly debiting my account for a non-existing account. I have just received an sms from my bank, Telkom debited 4 times the amount for this month (Feb). How do I solve this ? Please help!