repair centre is up to ****

I sent my iPhone 5s for repairs in Jan 2015 as it wasn't coming back on. Once received I was told we lucky we got a brand new phone. In Dec 2015 I had the same problem after my daugthers exams she put the phone off and it didn't come on. It was off for two weeks and in a cupboard. Now lerato tells me that the initial phone I recieved was refurbished as they only replaced the motherboard. Now she's accusing me of negligence and says I must pay for replacement of the new problem. My phone is still under warranty and I will not be paying for it. As I believe the problem wasn't fixed in the first place or I got the same faulty phone back. When asked her to speak to a supervisor or manager she says they all stepped out. When I questioned her her attitude decided to change. She even refused to give me the recording as she says I'm not meant to get it as its for internal use only. Seems to me they not aware of the consumer act in which I have a right to it. This service is pathetic. I want answers.