BDM review: Aleged debt to vodacom

I had a pre paid account with Vodacom. I have ported my number to MTN pre paid. I keep getting sms's and phone calls that I owe money to Vodacom. My current balance at Vodacom when migrated was about R 40 to my credit. (they owe me). I have called BDM they say that they have another name registered in my account. Well it's their problem. They would not stop harassing.