Unreliable Wonga

I had an account with Wonga and paid it up in full,I just saw last month tha I was handed over to Nimble group,I saw it from my Credit report,I was shocked because I knew I have paid this up last year 2020 January,I called Wonga they said I have reversed their collection I told them I can't reverse debit order above R200 they sai I should send my January last year Bank Statement,I did in the past three weeks they are telling me that they have no feedback for me since they have escalated the matter to their Finance Department,I have been calling for the past three weeks with no Feedback and this is affecting my Credit score so bad,can someone please assist me with this I am just drained by Wonga.