got new phone sent back

I got a Vodacom phone. sent it in for repair they replaced it with another phone. The new phone's microphone didn't work so I took it in the next morning. They sent that one in for repair instead of giving an out of box replacement phone. Now they tell me the new phone they gave me is irreparable? I was gobsmacked? I have been without a phone now for a month. I feel so helpless and there is nothing I did wrong.