Poor service on upgrade

I tried to upgrade my cellphone contract in January 2016. I upgraded to a I Phone 5s. the first phone I received was faulty. the micro phone was not working. I sent it back received a second one with the same problem. So they said they will send me a third one. to date I have not received it. I was willing to give them a chance for the third time but they still could not help me. I have been calling the call centre for the past 3 weeks. Every week the consultant makes false promises. they say it will be sent and the consultant I spoke to before did not release it. Yesterday was the last straw. the consultant told me that I will receive it the next day(10/03/2016) you welcome to check the call records. Only for me to called today and told it was not sent and I'm asked yet again if they must send it. this is appalling service.When I asked the consultant to check his previous calls to see why the previous consultant gave me false information he said he's trying to assist and he doesn't have to check previous calls there's nothing.I then asked him to cancel this upgrade as cell c does not value their clients. I will also be taking this up with Apple as to why defective phones are given