New phone not working

I upgraded end February to a Sony Ericsson M2 Aqua handset. I use the phone for my technician. The phone lost sim connection. I took the phone back in the beginning of March to have it checked out. Needless to say due to their poor service up till today I don't have a phone to use and the thing that is driving me crazy, nobody phone you back or the Menlyn branch do not answer their phones. I spoke to Sue (the manager) that promised she will phone us back (a month later) I still dont receive a call or sms from her. I spoke to Nadine Roesch on Tuesday last week, Promised she will phone me back within a halfhour, up till today no phone call received. This morning when I phoned, Sue (the manager ) is not available. But in the mean time I must pay my contract. I have to use an old Nokia phone. 5 Months down the line, I still don't have a phone, but I pay. I need a new phone. Not a refurbished phone. I pay for a new handset. I am sick and tired of their incompetence to solve this matter. Please help.