Credit card not updated

My credit card was handed over to Barrett and Associates Trust but I have settled the account. Some interest came in after my balance was 0 and I paid it. This account still shows on my FNB app and my TransUnion has not been updated after numerous calls to try and get this sorted as I need something on credit. Some can they sort this out ASAP as I am not sure whats the hold and never received the settlement letter,.