Poor service

I am utterly disappointed with MTN as I was a customer of theirs since I was 18 till last year and im 34 years.I struggled with payment of my last contract in 2022 but then paid it off in full last year September got a paid up letter from their collections company but they have still blacklisted after several times communicating with their finance department,today again I'm unable to purchase my personal things because of them and i jad the same problem with them earlier this year trying to purchase a device from them but couldn't cause I'm still blacklisted.Its just disappointing and disgusting service.