Incorrect debit order

My mobile contract ended with Telkom in August 2017, I sent a cancellation in July 2017 but it wasn't cancelled. I had to fight with Telkom on calls, branch visits and emails for months until it was eventually "cancelled". The debit orders are still going through on my account until now, I have called and asked for a cancellations and refund and was informed my cases were investigated and closed but I was just debited again!