phone brought back for fault within 7 days

On the 3rd of feb my mom bought a phone at foschini. The internet wasn't working on the phone and vodacom customer service tried asissting on the 4th. Vodacom then said they cannot assist further telephonically and the phone needs to go in . The 5th the phone was takenback to the store where it was bought. They refused to replace the phone. Yet the terms and conditions say you can bring it back for a new phone within 7days if there is a fault. Now we are told its sent in for higher repair. We want this phone replaced not repaired. A brand new thing cannot be repaired.