upgrade disaster

I upgraded my contract on Monday 26.03.2018. I the sales consultant confirmed that my current cell no will become a prepaid no and the contract will have a new nr which was my request before I started with the upgrade. I am not able to get calls or make calls from my current nr and was told when I called the branch in Vangate that my nr was cancelled. I left a message for the consultant to call me back and until today I had no reply. I have been calling the call centre to no avail. I need my phone line to be converted to a prepaid line asap.