Blacklisted by Vodacom while account is paid in full.

I entered into a contractual agreement with vodacom for a phone and simcard (2 lines) in 2021. In the second month of 2023 on 27 February I settled the account and I sent all the required documents to early contracts cancelations department. 4 months down the Iine I found out that I am blacklisted and my credit score is negatively affected, when I contacted vodacom customer care (collections)they told me no payments are reflected on their side and they cannot assist me. ASSIST ME VODACOM.