Samsung S6 not working

I upgraded my contract with Vodacom on 24 December 2015, and it goes without saying that I chose a samsung, as i have been a proud samsung fan since the S series was launched. i upgraded from my S4 to the new S6, and to my utter dissapointment, when i switched the phone on, it froze up, made a strange buzzing noise, and since then kept on rebooting itself repeatedly. i returned the phone to Vodacom, and still have not received a new Samsung, i never expected this from a brand new samsung device, and this makes me doubt if i even want a samsung again. I am now left without a phone, due to this factory fault, and wonder if samsung's standards have fallen? I am very dissapointed. What happened?