Failure to cancel account for a year

I cancelled my Telkom service a year ago, initially online and subsequently I have been in to the Telkom store three times re the cancellation. I have phoned, received and paid the final outstanding balance. Each time I am told the account has been cancelled yet I continue to receive invoices and messages from attorneys stating that the account has been handed over. I phoned again today and the lady from Telkom didn't even allow me to finish speaking before putting the phone down on me.