Afcho unfairly blacklisting me

Afcho is unfairly blacklisting me. They are saying I'm owing them. When I move to their bachelor flat they made a mistake of billing me for a 1bed flat. I tried to correct it with their caretaker Mr Vilakazi, with their customer services and Mbalenhle who is dealing with their credit but it was never solved. I finally served a 1 month notice in Nov 2019 hoping to get my R4300 deposit which I did not get. Few month after I started receiving messages that I'm owing R1050. I tried once more to correct it but still not assisted. Currently I'm getting emails to say I'm owing R2258 from their legal team(***) REF *** of which I tried to explain myself to them as well. How can someone owing serve a one month notice? And if I'm really owing them they still have R4300 deposit, why cant they take it from it and leave me alone.