Bad service on upgrade on damaged phone

I upgraded my contract at Standerton Vodacom shop on 25/11/2014 and got a new cat phone with the upgrade. The phone did not work and kept switching off by it self. I took the phone back on 01/12/2014 and told them the problem with the phone. The shop send the phone to the repairs with a OBF to have it replaced if the problem is a hardware problem. We closed for Dec holiday on 12/12/1014 and the phone was still not back at the shop. I only managed to collect the phone on 05/01/2015 and returned it on 06/01/2015 as the phone still had the same problem. The shop said that repairs could not find any problem. The phone was send back to the repair shop then to advance repair centre. Parts was changed on the phone and Vodacom wants me to take the phone which was repaired where with the upgrade I should have a new phone. I am still paying my contract and still do not have a phone which is with Vodacom. No person at Vodacom wants to help me and each one is blaming the other and I the consumer still gets a reminder each month via sms from vodacom to pay my bill . So what am I paying for if they can not resolve the problem with my phone and what is their guarantee worth ?