Not Replacing my phone after requested to do so

I upgraded to a Samsung S6 edge in August this year. After two months the phone started randomly freezing and switching on and off. By the third time I took it back to Vodacom for the SAME problem, it couldn't't even switch on anymore! Whatever they have done has made the problem worse! I went back to Vodacom, spoke to the manager, Riaan van Wyk, and told him seeing as my phone hasn't been damaged by me and is still in warranty I request a new phone. The device is obviously faulty and they don't know how to fix it. He said he will handle my request. However this request has been ignored and my device was still just sent in for repairs!! I am not willing to drive up and down and wait months for Vodacom to try and figure out what is wrong with the phone! I am the one paying R900 pm for a phone I don't have? I requested a new device and this has been ignored! Unacceptable.