Telkom is refusing to close a my phone contract.which ended 1 year ago

For the last year I've been trying to cancel my contract with them,but they do not want to cancel.they keep on sending me invoices saying I should pay they will close the account.after paying they send another invoice.i paid more than R5000 for a contract I. Not using....I don't get data or anything but they have the nerve to want now and then.for something I am not using.i called so many times I didn't get help.i was then reffered to Telkom Polokwane,they **** and said they closed the account.and they will email.proof.but they didn't