Debt Sold to Multiple Collectors!! Fix This.

I was under debt review and my debt was being handled by Consumer Friend and I settled the debt in May 2021. Now I am being contacted by Capital Data saying I owe R2216 on my Capfin Loan. I have a paid-up letter from Consumer Friend and I have tried to explain to Capital Data that this debt was settled months ago but they refuse to close the account. Now this debt is damaging my credit score as it appears as arrears. Please instruct Capital Data to close this account ASAP because I am fed up with this ridiculous service I am receiving from CAPFIN!!!