Pathetic service

I have a phone contract with MTN for the past 2years, for sometime i wasnt using my phone then evenually i started using the phone, know it seems like i have a cross line linked to someone else. ***, when i someone calls from a landline number theirs anothe guy answering the phone, when i get a call from a cell number sometimes it goes directly to vmail. My fiance sent me money via nedbank, i never received the sms so the other guy probably got the sms and got my money, i have addressed this matter with MTN more then once i have reference numbers of people saying they going to call me back todate no call... Ref number smc***