Telkom customers turned into milk ***s

We have cancelled a family landline which became useless since there were telephone lines problem in our are in 2016. We cancelled last year 17/02/2018, and even received a refund. Now Telkom has handed my wife over to their collectors because they NEVER cancelled the line and we have proof of our request confirmed by Telkom at that time. And now we must approach our legal advisors and attract unnecessary costs.