Sharing same MTN contract number with someone else.

Hi my name is Nthabiseng Ravhutsi, I have taken out an Mtn contract 2 months back at piet retief Mtn store, to my surprise I was told I will get data and Airtime but I have been receiving data only, ohk cool,I have been receiving lot of calls from different people looking for Sabelo Fakude, I was puzzled honestly because I mean who is sabelo and the numbers are also registered by the name of Sabelo, I thought maybe its the person who was using this numbers, however today I found my self chatting with the same person using same numbers as mine and he says he has been using this numbers since 2008,Contacts are(+***2)and he has registered this numbers all over, even on his CV and sometimes those calls comes to me, he tried calling MTN several times with no assistance, so what I am paying for exactly? And I remember I had to pay R150.00 for that sim card, but here i am finding my self sharing the same numbers with someone else, can this be sorted out urgently, either I get a new number or something must happen though.

Thanks.