Telkom- Robbing customers

I am writing this on behalf of my father. My father is a customer who has supported Telkom in Liberty Midlands mall from 2015 until date. He has never defaulted with payment as a debit order was put in place to ensure that. Recently, he is having endless problems with telkom . they are double debitting him and returning the money. Please bear in mind the second debit is higher than the first. This month my father got a call saying that he has been handed over to the credit bureau for an amount of R4000 plus .he has contacted telkom but did not get any joy. Please can we get assistance . Is this the way telkom value their loyal customers?