4 days on contract and still can't use my line

I converted my MTN prepaid number to a contract 4 days ago and since the conversion I have not been able to make any calls, send any SMSes or even access the data network. Incoming calls and SMS do work though.<br> I have called the MTN call centre 8 times already in the last 4 days and even went to the MTN store where I got my new phone. To date no one has been able to resolve this. 4 people have promised to call me back of which one only emailed me to inform she has heard nothing from the technical department as yet.<br> Surely someone must be able to resolve this?<br> Cherry on top will probably be that MTN is going to charge me for the days (weeks maybe even) that I'm not able to use my line...<br> Why can't anyone help me? Should I cancel this new contract and go to another network maybe?