Angry customer

I cancelled my Telkom line on the 16 October 2018, the line was cut on 16 November and my final account was settled immediately. Since then I am still getting invoiced monthly, to date I apparently owe R821.06 for a line that doesn't exist. I have called Telkom numerous times. The consultants keep saying that the 'order is locked' on the system and it's been referred to the supervisor. The matter is obviously not rectified as I am still be billed. I have a R700.00 deposit due to me and this will not be refunded until the matter is resolved. I am beyond angry now. Telkom I need this sorted IMMEDIATELY.