Paid up letter request & update of credit report!

I am having difficulty getting my paid-up letter from Nedbank for my credit card ***. I paid it in full on the 28th of November and have called them 3 times and each time I get told that it will take 5 working days to receive this letter. I have yet to receive anything from them nor a call from them. In addition to this, after 12 years, Nedbank suddenly put this account as in arrears on my credit score, and since it hasn't been on my credit score for over 10+ years, this is highly ******* and irregular and has caused my credit score to decrease heavily when I have paid this up! I've asked them to update things with all the credit bureaus or to provide me with the letter to do so myself and this has not been done. Terrible service!!!