Vodacom poor customer service, irritating calls and messages

I took over a contract almost a year ago, until this day I receive calls everyday when the other persons account is in arrears as well as sms`s, I have reported it to Vodacom and they tell me it is sorted but it is not. Support number: *** has been closed but the problem is not rectified. Support number: *** partially sorted out but still problem of hounding calls. Spoke to a lady at call centre after a call back who said she has spoken to the creditors department and they said is was sorted and her system said so as well, she said she would raise it with her supervisor. Why is it so hard to have my number removed from that persons profile.