Telkom FAIL!!!!

I canceled my business phone contract with Telkom in April this year, followed all the instructions, sent all the correct emails to the correct email addresses as specified, yet they are unable to cancel this account and insist on sending invoices every month, I have phoned them every month since then, RESENT the cancelation emails EVERY MONTH!!!! Yet they seem to fail to understand a cancelation email EVERY MONTH.... Are these people unable to read, or unable to understand what a cancelation email actually means??????