Wrongful handing over for Nudebt collection

In around March of this year I contacted Telkom to give them my 30 day notice to disconnect my home ADSL line. The operator looked on the system and told me that my line was managed by Mweb and that I should contact them regarding cancellation of the ADSL line. This was incorrect as I knew that MWEB did not but I contacted them anyway because I had to cancel the ADSL service as well. As expected MWEB told me that they could not disconnect the line as Telkom managed the line. I once again phoned Telkom and informed the operator of the fact. and requested that they please accept my 30 day notice to disconnect the line. The operator then said that they would. Then two months later I started getting calls from Nudebt collections saying that Telkom handed me over for R566.36 due to non payment, even though I had paid the last months notice on the account as well. The more I tell the guys at Nudebt the more SMS's and calls I get. Telkom says they cant do anything about it cause it's handed over. I have even asked Nudebt to take me to court so that we can sort it out there... But no, I keep getting threatening SMS's and calls. I want to sue them now already!!!