Account Remains Open after settling it almost 2 years ago

I had a Contract with Cell C in 2015, and the account is paid off years ago, however my account is still open when i check my credit score, how can the account that was paid almost 2 years ago still open today. I have been trying to call the legal department for the past 2 hours and the line does not go through, Can you please sort out this account. My numbers: ********** 647