*****ulent account

I have a loan and a credit card with african bank which I have been paying very well without fail. In July 2023 I started receiving calls from african bank consultants demanding the payment of the 3rd account which they said its an overdraft account which I know nothing about. Of the amount of R15 000 mind you i don't bank with them I just have 2 loans. I bank with capitec,I went to the branch several times did 2 affidavits,submitted statements showing them that I never received any money .he then confirmed and told me that he will send it to their ***** department. Till today I haven't received any help and every week I am receiving calls from them demanding money 🙃 every consultant promises to forward my complaint and now they are threatening to list me on credit bureau for the account I know nothing about. I even paid up my credit card so I can part ways with them and still struggling to get my paid up letter. Please assist