Upgrade Z5 dud 4 months old

I have sent in my new Z5 what I upgraded in January twice for repairs now and was unsuccessful again. I paid for a phone I didn't have for a month long just for repairs and is still giving me software and hardware related problems, I requested for a new phone or a different one but still they don't bother to give me a working device, please help. I'm stuck and I pay Vodacom alot each month but they can't reimburse my device or money's worth. Regards Ruan