Nimble Grouo do not send paid up letter

I paid up a debt earlier lastyear,never received a paid up letter & it’s negatively affecting my credit score-I sent my 1st request 4 the letter in October 24 as I wasn’t aware that the debt still appeared as uncleared- I called and was directed to WhatsApp, it’s almost February 25 & I’m still waiting 4 the paid up letter for something I paid up earlier in 2024-I’m tired of sending the request via WhatsApp & getting the same response since lastyear