Discount settlement

Good day,

I am extremely unhappy as I took up a contract with you and when I lost my job, i made the necessary arrangements with you, however when my account as handed over between 2***) the amount was R2800 (as per experian) and today when I called , my bill has triple the amount how is that possible? I could not even get a clear answer, although i have been paying since been recontacted by the attorneys .... How are you unable to assist with a discounted settlement because it is an old account?