Account Cancellation Problems (Causing bad Credit Score)

I cancelled and paid my account in full in January 2022. Since then I am getting harassed by their debt collectors to pay up my account. No matter how many times I tell them I paid in full, they request a paid up certificate or something from me, which I should get from Vodacom. I contacted Vodacom for said certificate, but I don't get any response!

No response from Vodacom or HP Attorneys! This is pathetic!

Now this is penalizing my credit score very badly!! Now I am getting a bad name because Vodacom can't even cancel my account correctly!! Not to speak about the harassments I am getting from HPD. Fix this Vodacom!! My name should have never even reached the attorneys!

NOTE: Vodacom, don't even try to call me on my listed number, I am not in SA anymore! Thus me cancelling the account!