Inconsistencies and Demands

As I have complained before about nimble and it's inconsistencies when it comes to balances. After I sent my review in Jan 2024 nimble group communicated with me via emails. I still complained that their balance don't correspond to balances on the statement. They promised me that one of their consultants will call with regards to a settlement. I wanted to settle the account and requested that they give me a discount but nothing has happened since then until on the 20th May 2024 I receive an email stating "Letter of demand" with a balance of R4840. What is all this? Nimble group give a discount so I can settle this account please I tired of all this.