Bad Service

I renewed my sons contract at the Campus Square branch for a sony phone. The phone broke within the 7 day return period , we took the phone back and they didn't change the phone they sent it in for repairs. After the repairs the phone broke again. We took the phone back on saturday they still didn't change the phone ,they booked it in for another repair. We are unable to cancell the contract as we just up graded now. According to the consumer council law within 7 days Cell C should change the phone for a new one