Telkom, yeah right, more like Teldom

My mother sold her house 2 years ago and we followed the required procedure to cancel the line, we called telkom and they advised that we need to send through a cancellation letter and they will then sort it out, as per they request I did what was required and I sent it through, so I receive a sms on my phone stating the the account has now been handed over to their debt collectors and my mother needs to pay the outstanding amount of over R2k else further action will be taken, first of all what I am so upset about is that we did follow their process and my mother is a pensioner, she is not plugging the telkom line in her backside and using their services and for them to keep harping for their mess up is just not fair on her or us as I am the one receiving all these love sms's. I tried emailing them but low and behold the email does not exist now, but I have all the proof of the letter sent and of the automatic reply received then from them so the process was adhered to. So please telkom sort out your mess up and fix this