Faulty phone - No replacement

Hi, I have a ZTE Grand X2, which I have on contract via Cell C. This is my second device in one contract term. The first device started switching off at random and one day just switched off completely. This device was replace with a new one, but same make and model. This happened all is 2014. Now in 2015, June the device started the same pattern, I sent it for repair and they said all is good. I had the phone for a week and the same problem reoccurred, I then sent it back again. Now that it is at the Repair centre for the third time, I have lost all patience and confidence in the device. I have asked Cell C for a new phone. Which the are reluctant to do. And I will be contacting my attorney, first thing on Monday to sort this mess out, as I paying for a device I never have the joy of! I would advise customers to be careful when choosing to sign up with Cell C,