Cell C Network issue

I have been with cell c for a while now and never had this much problems with the network. I tried to make calls then it gives me voice mail but the phone that I tried to contact is on, I first thought it was just my phone but my husbands phone is also giving problems. I wish I could cancel my contract immediately as it a waste of time have the phone with me and no one can get hold of me. When I contact the call centre they tell me there is no problems with the network, I should just buy myself a sim with another network cause Cell C is giving me too much problems and wasting my time.