Unhappy ex-Telkom customer

Telkom delivered a WiFi phone to replace our landline in December 2018 to a neighbour in our road. I did not sign for it. Shortly thereafter our land line service was stopped. We have been without a land line or any kind of Telkom line (I refuse to use their WiFi phone in the house) the whole of 2019. Telkom has continue to bill me for a fixed voice service even though I have no line to speak of and have not made any calls. I cancelled the line officially in March 2019 and have been billed up until May 2019. I have tried numerous times to get hold of a Telkom accounts agent with no real success in resolving this. I feel that they should not have billed me at all for the line in 2019. How can Telkom deliver a phone for which I did not sign, then cut off my land line and continue to bill me?