Unreliable Telkom Services

I had a Sim only contract with Telkom that I paid and closed. Now when I am checking on Clearscore it shows that the account is defaulted and not closed, I have been to Telkom branches enquirying why it’s still open and not closed and they told me they’ll close it after 6 months, not knowing after 6 months they will list it as defaulted, I’m very mad because that’s messing up my credit history, I struggled when I wanted to close their account and ended up paying through Woolworths and when you call their call centre they will not have any answers