Settled account credit listing

I have went through a rough patch and the end of my contract decided not continue my my contract to find i had missed payment of R483. I get it it was due u subsequently oaid via nimble once i becone aware when i was updating my creditscore and settled the amount immediatley. A year later many calls tp ADT their collection agents norman bisset aka nimble the listing still reflects, this is **** poor by Nimble as well.