Telkom - POOR SERVICE

My Telkom data contract had expired in Oct 2017 and till date Telkom is debiting my account. I have given Telkom notice to cancel my contract at the time in writing and verbally over the phone but they still continue to debit my account. Last month a case was raised with the billing department and they came back stating the issue has been resolved and the case is closed, yet this morning they debited again. Telkom service has really become terrible and I dont advise anyone to take any contracts with telkom.