Cannot cancel phone line

I cancelled my Telkom account (phone line, adsl line and subscription) over the phone in February this year when I moved house. But I continued to receive Telkom accounts in March, April, May and June. I paid the March account, because I assumed it was sent to me because I hadn't given sufficient notice of cancellation. But I refuse to pay the accounts for April-June.<br> <br> I have attempted to query this over the phone