VODAC *********** account staff

Hi have been contacted by their accounts department for the last three months telling e i am R135 overdue o my cell phone account. I had my number converted to prepaid at least a year ago and now according to vodacom i owe them R135. After numerous fighting matches and having been told the call was recorded they still call me for their R135. This is the incompetency we sit with as clients of Vodacom and they cannot even get something like this right