incorrect billing for an account which was not closed

I don not know where to start to express my disappointment. After moving out due to bad treatment, not receiving my deposit while my statement says refunded, my account not being closed from November till April. i had a bill under my name by Mafadi and after requesting them to correct everything i get a statement that says im in bad debt. Angela and Siphiwe were assisting on this case. I have never worked with such incompetence.