Mtn uses customers as gravytrain

Mtn , you are busy with *****ulent activities, this month my wife got an sms saying we owe you an payment of over R2000 , charging us for a device that my wife settled earlier than she should in October last year already , we even have proof on bank statements that we paid the amount according to your settlement quote, this is negatively affecting her credit score now, I will take this further by means of legal action if this is not rectified in the next day or two