Failing to cancel my service after almost two months

After repeated attempts to get my ADSL line properly investigated by TELKOM I cancelled my ADSL with my ISP. My ISP cancelled on time. However TELKOM still hasn't cancelled the analogue line and in fact billed me for the month after my service was supposed to end. I cancelled on the first working day of October which is Monday the 2nd. I checked again and found the line is still active. I will not pay for any period after October 2017. I am surprised that TELKOM actually still has clients