Sick and tired

I was handed over by Bonitas for an outstanding amount. They investigated and found that my previous employer had to pay the amount. When I explained it to them they told me to send the proof of payment. I exoleined that I dont know if they paid but they must stop calling me for the money. Well you know debt collectors. Its like talking to my children, they don't listen.

Hope after this they will stop bothering me for a fault that Bonitas made.