Network Problem

A few weeks ago I went to the branch in Menlyn to report error message I get on my cellphone, the guy who helped me was a white guy and he said it was a simcard error. I paid for a new sim and he said it will take 24 hours and then it will work. Still the phone gave me the same error NOT REGISTERED ON NETWORK. I went backand spoke to an indian guy there and he refered me to samsung saying that my phone is faulthy. Samsung said they cant help because it is a network problem so cell c must help. I called the helpline spoke to plenty people there and no one can help. Is there anyone at cell c that knows how to do they work!?!!!!!!. It has been for over a month. Still paying my contract but cell c is patetic!!!