Bad customer experience!!! 😡😡😡

I had a Wonga account that was taken to Nibmle Group. This year in March I decided to call them and set up a settlement for my account and I was advised that my account had a 45% discount therefore I would only have to pay R935 and my account would be settled, of which I did. On the 25th of March they took off money from my account and I was advised that I would receive a paid up letter. I didn’t receive any letter and I tried contacting them on WhatsApp then I was informed that my account still has a balance that’s why I cannot get my paid up letter. I just called today and I am informed that I am not owing anything that the balance still needs to be written off from their side. I honestly don’t understand how this company works and it is so frustrating 😡😡😡😡