MTN is deducted money that i do not

I have a serious problem with MTN ... They have been deducting in my account for the 24 Months and i dnt understand .. I have went to the shop Kollonade was told to go and write a Affidavit at the Police station . went back i was told i must call mtn because MTN needs to refund me .. This is the 2nd time this is happening . Last time someone open account under my name .. I was charge for the Phones i never had im my life . Now its this