Terminated contract with cell C - NO RESPONSE

I am not getting help from Cell C! I had a cellphone and router contract with them in 2018; both contracts were paid and closed/terminated in 2020. However, I have not received the paid-up letters I have been requesting. On my credit profile, these accounts are reflected as in arrears. I have visited the branch four times, Called customer care and sent emails. However, I remain ignored. Can they at least answer my emails or get back to me??