Incorrect credit record listing

I have had zero help from MTN regarding the removal of a paid up account on my credit record. the account was paid up in April 2023, a paid up letter issued in December 2023, however still reflects as active with and arrears amount on my record. The call centre refers you to a debt collector, where calls are left unanswered, I've attempting emailing them, since 2024, and still no joy.