********** activity on my account

I opened a Mr Price account and one of the Mr price staff members registered a Mr price sim card on my name since they have access to our ID Numbers. They bought 300 Rand worth of airtime on my account and i saw that when i checked my balance since it was drastically dropping every time i checked it and i called Mr price mobile to query this and they were unhelpful as they did not want to tell me who registered the sim card on my name and why was i not notified on my registered cell phone number. I asked for the cell phone number and called the number and i got an auto response saying the number does not exist, I will not pay for airtime i did not use and would like for this matter to be attended with utmost urgency as this is a ***** case.