REFUSAL PAID UP LETTER

I wanted to cancel telkom contract and they gave me the statement as to how much I will have to pay including cancellation fees. I did cancel but now I can't get the paid up letter as this is also affecting my credit score (ITC). I HAVE BEEN CALLING TELKOM BUT NONE OF THE AGENTS GIVE ME A WAY FORWARD AS TO WHERE AND HOW WILL I GET IT. They used to call me 24/7 raiding their payment during lockdown as I was not working but I kept depositing the monthly installments making arrangements with them. Now that I have paid all the money they are refusing to give me the paid up letter and this ****es me off because my life is stuck because in the ITC it shows that I still OWE them. At least if I could get a paid up letter stating that I don't owe them.