Cell C, please help!

I have upgraded my Cell C contract. My Sim card would not activate on the new phone. I have spent R80 phoning Cell C Customer Care because for some odd reason I can't dial 135 on my phone. The lady that I was talking to while I used R50 airtime in about 10 minutes (2nd call today) said my sim was faulty and was about to swop my number to the new sim. She said she would call me back because I had run out of airtime. It has been about an hour and I have still not had a call back from cell c and neither sim card is working.