Unexplained debits

I had a phone contract with Telkom a few years ago, and insured it with finrite. I lost my phone and claimed it, paid the access fee but finrite did not replace my phone until I posted at "Hello Peter". My phone was replaced but since then they have been deducting money from my account using Nu Debt of which I always reverse because I don't know what is this money for and nobody cares to explain. This has been going on for over 2 years now. It's so frustrating.