Nedbank Cr Card

I had a credit card with Nedbank which went into arrears. I resumed payments and on the 19th of March 2019 requested a settlement amount. I received a paid up letter that specifically stated "Account ***** has been settled, and your indebtedness is accordingly extinguished". I went back to them on the 20th of March requesting a settlement letter, once again, a paid up letter was sent to me. To my shock and horror, I have been handed to attorneys, receiving phone calls asking me when will I be paying the Nedbank credit card. Now I have noticed that on my clear score report, there is an active debt for Nedbank credit card for value R3275. I need to know why do I suddenly owe Nedbank when they have twice cleared me of this debt. I have the copy of the letter signed by NDS Credit Management.