Unacceptable Service

My Telkom account was handed over to them in 2016 and we agreed on a payment plan.My last payment to them was on the 31st of December 2016.I have been requesting a paid up letter since January 2017 and I still haven't received anything up until today,I call them on a weekly basis and they keep telling me that the letter will be sent to my email address which was provided to them on numerous occasions.On the 7th of August 2018,I received a phone call from Telkom claiming that I owe them money,so I decided to contact Nudebt again requesting the paid up letter,the consultants gave me a run around they kept on transferring my call to the next person up until I spoke to the supervisor who told me that the is no outstanding Telkom account under my name and she doesn't know why I haven't received the paid up letter,which she still couldn't provide it to me.Now I have Telkom calling me and demanding money which was paid in 2016.