Money deducted from my account even when contact has been cancelled

I canceled the Telkom contract in April and sent the Letter required and Id number. Unfortunately, there are still deductions on my account. I called and sent emails, but no one is responding and they are still deducting every month. Can someone from Telkom tell me what I need to do for them to stop deducting from my account? And I need my refund, please. All the monies have been deducted since April. Thanks