Billing after services have been terminated

I cancelled all my telkom services on the 29/09/2017 in which was my 30 days notice which my services were terminated on the 29/10/2017 at midnight! i also received an sms on 30/10/2017 that you are sorry see me leave you! Now i receive an account for the period of 9/11/2017 to 8/12/2017 but my line isn't even active??????????? I contacted your billing department to find out what's happened and they don't know and say my services are still active yet my line is dead. All they could say is they will escalate the issue??? how long is this gonna take?? My account better not be debited for these services which i cancelled well within the time specified in my contract and my line is dead so I'm not even recieving these so called services.