Unable to provide breakdown of amount they say is owed

My partner has been told that his cheque account with standard bank which has now been closed has been handed over to Nimble for collection.For the past 2 month all we have done is asked for a detailed breakdown of what makes up the rolled over amount of 3685,55 which they havent assisted with, all we get is rude consultants and when we tell them what we want they keep sending us the same 1 line statement with just the balance.We would really appreciate a breakdown in order for us to understand wat we are paying for