Cannot make any phone calls

I have a new Neotel prepaid phone, which is now about a month old, and as of Friday I am unable to make any calls from the phone - keep getting a messag 'emergency number only' when I try to phone. The phone is charged,has airtime on and I have put the phone on and off, battery and sim out, several times. I called the call centre and after they have again told me to take the battery and sim out without success, they said everything on their side shows the phone has no problems and should be working. This is not acceptable as the phone does not want to work and they cannot assist me. The call was escalated to the technical department, I'm still waiting for feedback. How do you expect me to run a business if I cannot make any phone calls??? The call centre person just said she cannot assist me further.