LG refuse to repair second-hand Swappa bought phone

I recently bought a barely used LG G4 from Swappa. I've been using it for about 2 months or so. The phone was running stock and as of a few days ago it went into the infamous bootloop problem. I called LG and they said that my warranty is voided because I had bought the phone second hand. I find this to be pretty ridiculous because the Bootloop problem is a hardware defect by LG, why does it matter if it is second hand or first hand? And right now they are refusing to repair it unless I have a proof of purchase from the original seller (He doesn't seem to have one/ lost it.) Any advise on how to proceed on this? I am pretty pissed that I spent 400$ on a flagship phone that isn't a year old with manufacturing defect and NOW without warranty. (Canadian variant of LG G4)

from xda-developers http://ift.tt/1SCW59X
via IFTTT