cheap LG relacement for my Sony Xperia

I got the Sony xepria cell phone on contract from Vodacom and they gave me a cell phone that has been problematic from the beginning they gave me a apparent new sim card but the number belonged to someone else and still receive phone calls from the previous owner friends. its been freezing too and could not answer the phone its my business phone and its very important that its in working condition at all times so I took it into the shop today to a guy call clement than gave me a cheap LG to use while being repair is inconvenient because I cannot access my emails or any of my media accounts and cell phone banking or do anything on the cell phone they gave for me to use. im upset as customer to be treated like this when I pay R680 per month.