Account settled...Horrible service

I have contacted mbd for my outstanding balance and I was assisted. I have settled my RCS Account August 2017. After a week i received a call from mbd consultant stating that I owe them.I requested my paid up letter but I was told that my account is not settled. STOP sending me Sms's as the account is up to date. I'm receiving sms everyday when I return a call they keep telling me that they will stop sending me Sms. Paid up letter was sent to ********** and to ********** on the 28/09/17 and 04/10/2017 but response received. Today again I spoke to TOTELO the supervisor who also told me that I'm owing R500 something within a month that I have settled the account. I would like to receive paid up letter with zero cents owing and sms should STOP ASAP. They must fix their system and mistakes they doing.