money paid but they handed me over

I am not happy with altech netstar, I cancelled the contract and I paid the outstanding amount of 1,040.00. on the 04 march 2015 and i was told that the account its settled ,Now I got an email that am a bad payer saying I must pay R R2618.82 and please explain why I was not notyfied .and no one contacted me that the is still outstanding amount.the email received on the 29/03/2015. and all the messages from credictworx was i have to pay R1.040.00 . of which i did.and confirm with them with the ref ALT015885 they have received a payment..now they have Hand Over to blacklist.and it was handed over after i have paid the R1.040.00. y no one phoned me or sms me like the normaly do......<br>