Contract still not canceled after a year

I am very disappointed and frustrated with your service as I have paid up my contract with you guys last year August. This year I checked my credit score and my bureau details show that I am in default with MTN account and when I followed up on the matter it was said that it was because of delayed cancelation and they fixed it... But to my surprise months later again I received an sms stating that I am being handed over for what reasons I do not know... I have been following this up for the longest time and still there's no resolution and when they transfered me to retentions department it shows that there is no outstanding balance but I was still handed over.. This very frustrating as it has ruined my life because I can't seem to apply for anything because of this!!!!! My name is Nelisile Sambane contact number ***. I can't even remember my contract number as I threw away the sim card after paying your phone off