Extremely rude service

I just received a call from an old mutual debt collector and she was extremely rude and had no way of speaking. Our company recently went through a bad time and had to retrench people and cut others salaries. I kept trying to call old mutual to inform them but they did not assist so I had no choice other than to reverse the debit orders because I was earning a lot less after couple months the issue was resolved and arrangements were made and now this extremely rude person calls and say since they assisted me with the arrangements I haven't paid so I ask her from when and she doesn't even have information, how can you call someone claiming these things when you have no information, I have been paying since the arrangements and still old mutual sends me sms saying its unpaid, what are your'll doing with my money