Worst Service From Impact Meter

I have an Issue with Impact Meters a company that is based in Centurion, They manage Electricity Bills for a complex where i used to rent in Midrand. When i moved out of the complex i requested that they send me all the balances that i owe them, which they did and i paid balance. they later came back this month and sent me another bill of R146.94 which i asked what is it for? and i was told that there was mistake on their side,, the lady who was working on the account didn't capture it right. We then arranged with a lady called Sandra that we will pay the amount month end,which she agreed and we received confirmation with SMSes that an arrangement was made. Today while i was minding my own business and thinking that this has been resolved i receive another SMS that indicates that my account have been sent to ITC for blacklisting.