What about the consumer law?

I recently upgraded on a contract to the SonyZ3,after 2 weeks,took it out of my pocket and had a ghost crack(researched it on the internet)Sent it back to CellC for replacing this phone,cause it did not fell(no marks on the phone nothing)not human fault! Got a quote today from CellC for repairing this phone.Will cost almost R4000,wanted to cancel this contract,but they are telling me I will have to pay over R12000(cost of the phone)to cancel this contract. Now I want to know about my rights as a customer,and the consumer law,as this phone was returned before 30 days? I have been with CellC for more than 10 years,and never had a problem with their service,till now. Why can one buy a washing machine and if there is a fault,it is replaced or repaired without cost to me? Why does this not apply to a cellphone contract? Which you take out for 2 years and this is what you get?