proof of purchase

I booked my samsung s5 in for repairs at the walk in repair centre in century city on 1 Mar 2015 . The lady behind the counter had me sign a waiver of some sort which I did not read. She explained to me that it was because I did not have proof of purchase of my device. So I took it as I have signed this document, therefore I don't need proof of purchase. The lady then proceed to register the device and book it in for repair. I was told I would get my phone back on Tuesday, 3 Mar 2015. On Tuesday having received no feedback from samsung, I called in to enquire about it. The repair was not complete. The next day again having received no feedback, I called again, and the phone was ready for collection. I then went to century city to collect my phone. Once there I was asked to produce my proof of purchase. I was never told to bring along proof of purchase. I then asked to speak to the manger. I spoke to a lady and a gentleman. He told me the only way i would get my phone from them was to un-repair the phone. as there was no way he would release my phone without PoP. I argue that the phone was under warranty. The S5 was release June 2014. all S5 phones are under warranty. No phone phone